Has there ever been one of those "who wants to play the drums?" moments in a concert where the guy just trainwrecks?

Some guy in a wolf costume repeatedly invaded the stage and hijacked His Name is Alive's set at Bowery Ballroom, I think Psychic TV was the headliner. Each time, he grabbed the mic and took over as the frontperson, doing (apparently) his own material, and the band seemed happy enough to back him. Until security violently removed him from the stage, only for him to return minutes later. HNIA must have been in on it.

At one point he was going around asking everyone in the audience their age, and whatever number they said, he would announce "that's much too young, you're going to die!!"
Only part i remember

Oonglebinky (my band of one day in high school) covered "Jump in the Fire" at our only show, and our lead vocalist didn't know the words, and I assholishly didn't let him take a sheet of paper on stage, so he just kept yelling "YEAH!" during the song instead of singing lyrics.

he invited someone out of the audience to sing after two choruses, and the dude couldn't sing, he just talked the lyrics, but unfortunately he started doing the verse when we were in the bridge. he jumped off stage at the end of the song. it was bad.

― cancel culture club (Neanderthal),

I had this friend in high school who had been to guitar camp, we used to do a rendition of a certain classic rock standard (which i won't name) with him on guitar and me singing as horribly as possible, just to try and massacre that song. He wanted us to do it for the school talent show, but I didn't want to, so on the night he got me to drink revolting malt liquor until i agreed to it.

So we entered the talent show, I was wasted, and the folks in charge were none the wiser. We needed a terrible drummer, though. There was this kid in the year above ours walking around backstage in swim fins and a diaper, so i figured he'd be perfect and asked him to play the drums. He thought I was under some mistaken impression that he actually played the drums, but I assured him it wasn't an issue. He obviously thought that was the end of the duscussion, though. Before we went on, we asked him again and he reiterated that he does not play the drums. I don't think we'd actually let him in on the joke, that we were planning to annihilate the song.
So we played the song with the kid in a diaper cluelessly bashing away, it went really well (i.e. horribly), so we decided to do a second number. As i was announcing the next song, someone closed the curtain.

THE ARISTOCRATS

Yeah so there's a door to door salesman, he knocks on the door and a kid answers. The kud is wearing swim fins and a daiper and holding a martini. So the salesman says, "Hey kid! Are your parents home?" And the kid says, "what do you fucking think?"

in our band, coincidentally enough, we hired some dude to play drums day of, but he actually did know how to play and learned his parts on the fly. he was the guitarist for the other band.

no diaper though

See, the daiper is key. Part of it was, the kid had a look and a vibe a little bit like the "disco sucks" kid from that 70's show, i knew he'd be down to play some classic rock. Probably why i didn't tell him we were going to do it badly.

That is a funny coincidence tho

Some guy in a wolf costume repeatedly invaded the stage and hijacked His Name is Alive's set at Bowery Ballroom, I think Psychic TV was the headliner. Each time, he grabbed the mic and took over as the frontperson, doing (apparently) his own material, and the band seemed happy enough to back him. Until security violently removed him from the stage, only for him to return minutes later. HNIA must have been in on it.

At one point he was going around asking everyone in the audience their age, and whatever number they said, he would announce "that's much too young, you're going to die!!"
Only part i remember

this is the best live music story i've ever heard

All gigs should be like that. Why aren't all gigs like that

-I remember seeing Common once, and he had a segment where he'd pull someone up from the crowd to freestyle with him. He brought up a little kid who was incredible, but I'm sure it must have backfired sometimes (although it's a good idea to choose a kid, because it's cute even if they choke).

-the famous Lars-less Metallica gig is also the opposite of this, where everyone got to live out the thought experiment of 'what if Metallica had a different drummer?'. Would have been amazing if Dave Lombardo had done the whole show.

-I have seen wack horn players sit in with New Orleans brass band countless times, but they generally can't do too much damage since there are enough people covering the parts for real.

feel like the next step is for Metallica to have a Metallica-less gig

four random dudes show up at show time and start playing, at various skill levels

That's arguably a description of the first Last Exit show.

...although they weren't playing Metallica songs.

-I remember seeing Common once, and he had a segment where he'd pull someone up from the crowd to freestyle with him. He brought up a little kid who was incredible, but I'm sure it must have backfired sometimes (although it's a good idea to choose a kid, because it's cute even if they choke).

i saw ghostface do a lazier version of this like 15 years ago, where he just invited people from the crowd to come up and rap on their own while he sat out, he may even have gone offstage. every one was terrible and it was like 20 minutes of his 45-minute set, felt like a ripoff.