If you want to avoid looking like Michael Scott at your friend's wedding, take notes and try not to be this awkward.
Epic

Ok, here it goes. I used to be a cake decorator. I did this for 14 years. I made all kinds of cakes, including wedding cakes. Wedding cakes were considered a big deal with my employer and insisted that I stay for the wedding and or the reception, depending on where the cake was. In 14 years I averaged out to 35 wedding cakes a year, so about 490 wedding events, of those I’d say about half were wedding/reception combinations. So I’ve got about 200 weddings I have experienced. Surprisingly I have never heard anyone speak up during the “speak now or forever hold your peace” bit. The one story I would love to share is this. This was an early spring wedding, the original plans called for an outside wedding but weather brought us indoors. Other than that the wedding is proceeding as expected, and we are at the point where the religious figure is asking the groom the “do you take whatever to be your lawfully wedded blah blah blah”, the groom says no. The crowd goes into gasp, mumble and whisper mode. Nice, something different. The groom looks to the back of the room and gives a hand signal to someone near the lights. The place goes black, and a flashlight comes on and the groom is using it to fiddle with an AV cart with one of those older projection units that could project onto a wall or screen. The thing comes to life and the groom, the bride, and the brides family are all lit up in the beam of the projector. The groom announces that what we are about to see was filmed the night before the wedding. He walks over the the machine and presses play. Immediately the room is filled with the moanings, groanings, slapping, and slurping sounds of two people really going at it. As the projector finally focused, we see superimposed over the bride and her family the bride going at it with the best man total porno slut style. I watched as the bridal party were shocked into complete silence and motionless. The video played for a good 45 seconds to a minute before any of them showed any reaction. The bride crumpled to the ground crying, and the mom and dad pried her off the floor and walked her out. The place is still dark as night except the front, I stand at the back for a quick exit (you learn after the first 3 or so where to hang out for a quick escape), I applauded and then left. I never did find out what happened after that, but I am happy I got to see that happen. (Source)
“The 3 Drink Grace”

At my brother-in-laws wedding the grandmother of the Bride was asked to say grace before the meal. My father and I happened to be standing by the bar after getting one last drink before it closed during the meal. We figured we would stand there during the 30 seconds or so while she blessed the food. She pulls out 3 pieces of paper, completely full front and back, and starts in on the history of the Brides family. Here is what so and so is doing now. When and where everyone has moved into their current homes. Updates on nieces, nephews, cousins parents, grandparent, everyone. No one knew she was going to get up there and talk for 15+ minutes about people nobody cared about. My dad and I actually finished our drinks and ordered 2 more by the time she was done. I refer to it as “The 3 Drink Grace”. (Source)
Yikes

My cousin married a mormon boy a few years back. Our aunt officiated it and our entire family was so proud of her, and all loved the guy. The guys’ mother though was very into her religion, almost convinced the groom’s entire side of the family not to go because my cousin had visible tattoos but the groom and his brothers convinced her not to. At the wedding she broke into a toast that was not planned, nor requested, where she essentially said that she hoped that during my cousin’s life she could look to the LDS church for truth and hopefully be able to ask God for forgiveness for her sins and be allowed into heaven. There was a very awkward silence afterward, with even most of her family looking embarrassed but was broken by my aunt yelling out “We love you Libby!” which prompted lots of cheers. The groom and some other cousins of mine promptly “asked” the mother to leave while others of us consoled the bride who was in tears. (Source)
The “Recovering” Addict

I got this one nailed. Wedding in North Carolina. Father of the bride is also the pastor. Brides’ sister is a “recovering” addict who has been clean long enough to be trusted to be a bridesmaid. Big mistake. Starts normal enough. Bridal party and bride and groom all up there and pastor (father) starts talking. Then I notice bridesmaid sister slowly falling forward and catching herself a few times. Then she starts swaying even more. Pastor notices but keeps rolling. Swaying gets worse. Friend of the family gets up and goes to stand behind her to catch her in case she falls. At this point she decides it would be a good time to ask her mom (in front row) to borrow some money. She does so loudly. Mom and everyone else ignore her but she asks again more loudly. It’s clear by her speech she is lit — at this point the pastor pauses and asks her to be quiet. Wrong move. She begins to berate her father, the pastor using language not intended for church. The family friend standing behind her tries to lead her away but she turns and slaps him. He picks her up cavemen style over the shoulder and starts to walk out a nearby door while she is screaming. He walks through the doorway and she grabs the frame and holds I. He breaks away but not before the bridesmaid gets in a few more f bombs. The the pastor finishes like nothing happens. (Source)
Wrong Speech

At my parent’s wedding the priest started with “We are gathered at this funeral today…” the worst part is he started going on with the typical funeral speech until he was stopped. To be fair he was well past retirement age. (Source)
Awkwarddd

At my cousin’s wedding, the priest made a long speech going on and on about how wonderful and responsible it was of the couple to get married once they got pregnant out of wedlock. Most of the bride’s family did not yet know she was pregnant. (Source)
An Unfortunate Surname

My cousin married a girl who’s surname is Fagg. There are a lot of them, lots of extended family. It is quite a sensitive subject for some of them. One of the best men in his speech said how he had lived with the groom for 6 months in Canada, which apparently qualifies same sex couples for marriage? So he was saying how he was the first one to marry the groom. The second best man said “well that explains why he married a Fagg”. Silence ensued. (Source)
AWK-WARD

Groom’s father made a speech along the lines of “we knew she was a keeper when he brought her home and we heard them f*cking in the bathroom.” AWK-WARD. (Source)
The Attention Getter

The groom’s mother (who apparently has issues) faked an epileptic fit because the bride was getting too much attention. (Source)
Double Meaning

When my husband and I first started dating, he took me as his date to the wedding of a friend. During the reception, as the groom (my husband’s friend) and his new bride was dancing to a nice romantic song, the DJ suddenly switched to “Sittin’ On The Dock of the Bay” by Otis Redding. This was the mid 1990’s and the song was out of place considering the other music that had been played so far. As I watched the couple dance, I noticed that the wife had this look of disgust on her face…and her husband seemed to be pleading with her….he looked upset, but she looked PISSED. I nudged my date and asked what was going on and he told me that the song had a double meeting. Groom and bride broke up once and he hooked up with a girl….on the dock, of the bay. Ta da! His friends knew about this (some sort of drunken encounter) and he confessed to his girlfriend when they got back together. His “friends” (using that term loosely) paid the DJ to play the song, which resulted in one pissed off bride. Pretty tacky of his friends, I thought. You don’t do that at someone’s wedding. (Source)
Definitely Memorable

I asked my dad to walk me down the aisle for my wedding. My dad – well, he’s a bit of an odd fellow. Probably has Aspergers, very socially awkward, but he means well and his heart is in the right place. He was very proud to walk me down the aisle, and wanted to make sure he did a good job. So he polled some married female friends of his to get their thoughts on their experience walking down the aisle. Most of them replied with some variation of “Oh, there was so much going on and it all went by so fast. I don’t remember too much about that part, actually.” So my dad, bless his heart, took that to mean their biggest regret was not making the walking down the aisle part memorable. So he decided he would have to MAKE. ME. REMEMBER. All of this he explains to me, just as we’re about to begin the procession. He says “Don’t worry DBplatypus, just follow my instructions.” And so we begin to proceed, and just as we near the rows and rows of people, he begins barking instructions. “LOOK OVER HERE! NOW LOOK OVER THERE! SMILE AT THIS PERSON! COMMIT!!! COMMIT THIS TO YOUR MEMORY!!! NOW LOOK BACK TO THE LEFT. NOW THE RIGHT. SLOW THE PACE DOWN! NOW LOOK TO THE FRONT! LOOK AT [FIANCÉ]! SMILE AT [FIANCÉ]!” And so on and so forth, all the way down the aisle. Meanwhile I’m trying to communicate to him through the smile plastered on my face “Yep, yep, it’s okay, I think I got it.” And everyone watching was shooting us confused looks. Well, I guess it worked, cause it’s not something I think I’ll ever forget! (Source)
Not So Subtle

One wedding I went to, the pastor started giving the typical “marriage is hard work” speech. He talks about how many marriages fail, and all the people he’s counseled through divorce. He goes on about how that on their wedding day, they’re just like this couple and who think they’re going to make it but 6 months later they’re getting a divorce. I’m trying hard to keep a straight face, the groom is starting to look like he wants to punch the guy, and I can hear people behind me disguising laughing as coughing. I keep expecting him to bring it around to something positive, but he doesn’t. 15 minutes of, “Marriage is hard and lots of them don’t work.”
Find out at the reception, he was a family friend. With a lifelong unrequited crush on the bride. (Source)
He’s Got A Point

So I was at my brother-in-laws wedding. My wife (grooms sister) was in the wedding party so I sat with her family. Her parents get up on the stage to say their speech. Father in law steps up to the mic and says: “Thanks everyone for coming out,” and sits back down beside me. There is a horrible awkward silence in the room, everyone was expecting a long speech, and the MC had just sat down and taken a big drink. In the silence he leans over to me and says: “What? If you don’t have anything nice to say!” Apparently he doesn’t like his new daughter in law very much! (Source)
Very Tense

When my cousin got married, most of the close family knew that the groom had been caught cheating multiple times in the past but the majority of the people attending did not. During a small speech discussing the marriage counseling he had done with the couple, the priest went on a long rant about the grooms past infidelity and how he was confident it would not happen again. Given how few people in the church knew about the issues, it became very tense. (Source)
Wasted

My wife’s aunt was wasted at my sister in law’s wedding and began a toast talking about the bride and her husband. After about 20 seconds she started talking about her dead parents and her failed relationships. She later tried (awkwardly) to have a friend of the groom dance and dip her which resulted in him dropping her on the floor and walking away while she rolled on the floor showing her sequin underwear. (Source)
The Alcoholic Uncle

At my sisters wedding, my alcoholic uncle went up and said a couple words. Them being: “I’m surprised you managed to have a successful wedding, how did this happen without your mom being the over controlling b*tch that she is?” A silence like no other. (Source)
Not Happy At All

Went to my uncle’s wedding a while back. His bride had been divorced and chose her family pastor to officiate. The pastor called my uncle her ex-husband’s name during the vows multiple times…my family was not happy. (Source)