Edit. Someone asked if these incidents occurred at the same wedding, a very good question. The answer is, no, they happened at different weddings. The world has no shortage of ill-mannered and socially-inept people who might get their hands on microphones.
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Really bad toasts and tributes.

(1) The groom had been engaged before, and he'd canceled his first wedding just days in advance. His choice was the right one, but it was nonetheless a painful, difficult, embarrassing decision, something best left in the past.

When he did marry another person, some years later, his brother was best man. Brother began his toast by crassly teasing about the broken engagement and last-minute cancellation. He started with a series of supposed jokes about:

-- Can we really believe the groom had shown up this time?
-- Who thought he'd actually go through with it?
-- Did the guests think they'd be together that day instead of getting cancellation phone calls?, etc.

None of this was funny; it was all cruel. People were glancing at each other awkwardly. The newly-married couple stared at the floor and tried to laugh uncomfortably.

Nearby relatives started telling the best man to stop it. But, no, he was on a roll, and he continued his stand-up routine. Finally, a middle-age aunt approached him, grabbed the microphone from his hand (much like taking a toy from a naughty child), and walked away with it. After a few moments of silence, the music began playing.

(2) The groom's brother-in-law thought it would be hilarious to roast him about his former drug use. The drug use had been long-ago in the past, when the groom was young. By his wedding day, he was a responsible adult, working in a high-power job for a conservative Wall Street firm. BIL did his routine in front of all the assembled people, including the groom's own parents, his new in-laws, and some bosses and colleagues from his job. That was at least 15 years ago; the groom still won't talk with BIL.

3) This was another groom's brother as best man. When it was time to toast the newlyweds, the best man stood up, raised his glass, and said, "May the bluebird of happiness crap all over you!" and nothing else. The couple didn't think this was funny, and neither did the wedding guests. The best man thought he'd been witty and clever, and he couldn't understand why nobody had laughed.

(4) The groom was a prolific hugger; when he encountered someone, even a casual acquaintance, he tended to grab the person in a huge bearhug. Some people were ok with this; other people weren't. At the guy's wedding, one of his friends decided to make jokes about this tendency.

The gist was: the groom will hug anyone and everyone. The teasing kept escalating; he hugs the mailman, the auto mechanic, the cashier at the grocery store... None of this was true, of course, just in fun.

Then, the friend took things too far and said that the groom had even hugged Josef Mengele. For anyone unfamiliar, Mengele was an SS officer and physician at Auschwitz who helped select victims for extermination and performed deadly, agonizing medical experiments on human subjects. This was at a Jewish wedding. The entire room went silent in stunned disbelief. How could anyone think that would be funny? The friend awkwardly wrapped-up and sat down.