I don't know if this counts, I was more of a passerby than a participant ...
I subbed for a band of moonlighting forty-somethings (of which I am one). Most of them had played in bands at some point, except for the lead-guitarist, who predictably was the biggest know-it-all of the group. No matter, I'm pretty good at pretending I'm listening and he wasn't messing with me too much anyhow. The singer's dad has sung for bands going way back, so he shows up at gigs and runs sound for them for free when he can. Knows what he's doing.
Their bass-player left the band, mostly over conflict with the lead I think, so they asked me to join in his place. I agreed, but it was close to Christmas so it was going to take a couple of weeks to get our rehearsal schedules in sync. Two weeks rolls by and I email the lead-guitard to see when we're going to get together. He responds with some whack line like "the fact that you haven't heard the news just shows why I quit this band", or some such stuff.
I called up the other guitar player to get the scoop ... turns out Jimi-wannabe had been having issues with the volunteer sound guy over -- surprise, surprise -- not turning his solos up loud enough. (Trust me, the guy's solos weren't worth turning up). After the bass-player leaves, guitard-boy decides to call up the sound guy and essentially fire him, without bothering to consult the rest of the band over it. The sound guy politely replies that he'll see what the rest of the band thinks and blows him off. Needless to say, the lead-singer is hacked (it's his dad, remember), so he and the guitard have words (or emails) that eventually escalate into bright-boy insulting the lead-singer's whole family, including his wife. For real -- complete kindergarten stuff. It ended up that he quit, but there's no way he could have shown his ugly little face anywhere near them anyhow.
Oh, and as a parting shot, he called and canceled the gigs that they had on the calendar, including the ones he hadn't booked. Even took one of the gigs he "canceled" for us with a different band, but I heard he sucked with them too.