Three spring to mind.
1. A relative decided to have an outdoor wedding in July in
TEXAS at about 1:00. There was not a shade tree to be seen and no cover provided. It was just shy of 100 degrees.

The guests who weren't melting were about to pass out.

I had mentioned to DH that I didn't know HOW the bride was going to make it through the ceremony in her huge, bouffant, hoop-skirted (okay, at least a massive petticoat) dress. That thing was heavy. Just before the bride comes out, the elderly grandmother, who has reached the age where she feels entitled to say
anything, blurts out in a near-yell, "Whose bright idea was it to have this wedding in the big middle of the day in this heat, anyway?"

She was only saying what we were all thinking. So the bride walks out in her biggie dress and she looks cool as a cucumber. The ceremony progresses and she continues to not perspire in the slightest.

Finally, I muttered to DH, "
I think she's got a window unit air conditioner up underneath that hoop skirt." 
They got a trememdous round of applause when they were pronounced husband and wife, simply because we knew we could now go inside and get some relief. That was over 20 years ago and they are still married.
2. A girl I'd known since kindergarten was getting married to a nice enough guy, but everyone from her friends, to his family, to her family, to the cashier at the grocery store could tell you that marriage had no chance of lasting. I went with two other friends (also known them since kindergarten) and we drove across Texas to that wedding. The whole time, we reminisced about all the good times and near-disasters we'd gotten into since we were five years old. At some point, we drove through LaGrange and it struck us as hysterically funny that we all simultaneously belted out, "how, how, how...." (ZZ Top reference) I'm sure 90% of the people who hit the LaGrange city limits do the same thing.
We found ourselves essentially analyzing whether he would call off the wedding or she would and if so, would they do it before the actual ceremony began or would it occur during the ceremony. Seriously, that is how bad it was. We arrived and discovered that pretty much everyone else, family included, was doing the same thing. The ceremony started and the bride began to walk down the aisle. I kid you not, she was shaking so bad that the petals were flying off her bouquet.

She sort of served as her own flower girl. That bouquet was falling apart with every shaky, convulsive step she took. When they got to the part of the ceremony where the minister asks if anyone has any objections, there was an
AUDIBLE intake of breath throughout the church and everyone started looking at everyone else.

It was like, "YOU say something." "No, YOU say something, I'm not going to say anything." ACK! They were divorced within about 3 years.
3. A childhood friend was getting married. Again, I'd known her since I was 5. I was home from college and really wasn't planning on going to the wedding, but her daddy saw another friend and me that morning and asked if we'd be there......and of course, we said, "Yes, sir." We knew the guy she was marrying was from a family of Class A Rednecks, so there was no telling what was going to be at that wedding.

At first, it seemed to be going okay. His side had a few females who were wearing some seriously heavy makeup, but nothing too bad. Then the bridesmaids started down the aisle. I don't know WHO picked those dresses, but they did not consider the girls' figures when they did it. Every girl, save one, was very well-endowed and the dresses were empire waist with a teeny ribbon just under the breasts. All you saw coming down that aisle was......Well, you can guess. Speaking as a well-endowed woman, I'd have never worn that dress. Then the bride came in and her dress was snow white GLOWING satin with a train that must have been 25 feet long. I think they were trying to beat Princess Diana. Problem was, the bride would have to stand on a stool to be 5 feet tall. It was just strange.
Then the real show began....The groom and groomsmen gained our attention. We noticed that the groom was downright maroon in the face. Had he gotten the worst sunburn of his life? And why did his groomsmen (relatives) look so bleary-eyed? Yes, they were still drunk from whatever they had done the night before. And the groom's collar was way too tight. He wasn't sunburned....He was losing circulation. At some point, we couldn't hear his vows anymore and then he just locked at the knees and passed smooth out. Plunk!

I'd heard of brides fainting, but seeing that big old bruiser of a guy faint was unexpected. Being drunk and choked was not a good combo.
For a few seconds, everyone froze and there was silence. Then the bride bellowed, "MAMA!!!!!" People started trying to revive him, to no avail. Finally, he had to be carried out and it took awhile to bring him to. My friend and I have a dark sense of humor and couldn't help it.....It stuck us as funny. No one else in that huge crowd looked remotely amused, so we pinched each other to stop giggling. The bride was wailing loudly and finally, the organist had the presence of mind to start playing to cover up her crying. Eventually, the groom was hauled back in, but he was staggering. The best man had to help a bit to get him through it. The minister said the remainder of the vows as fast as an auctioneer.

When the bride and groom walked down the aisle, he looked confused and she was pissed. Lord, she was little, but once she got mad, you did not want to be on her bad side. I am sure he got his rear end chewed out that night.

They aren't still married.....He died in a car wreck a few years later. I have no idea if they would have lasted.