You remember that friend you had who was really hilarious at parties but would occasionally burst into tears or get into fights for no reason? You kind of had to do a cost-analysis with him: On the one hand, he was the funniest guy you knew. On the other hand, he would occasionally get too loud and say inappropriate things that would hurt people's feelings, and you'd feel like shit all of a sudden. Or he'd piss off someone's boyfriend and you'd have to run away from the party before you both had the shit beaten out of you.
Anyway, you know when that funniest friend you had started looking a little bit older—he had some wrinkles around his eyes, and his ironic novelty t-shirts started getting a little bit snug—and he started overcompensating by getting more and more offensive? Remember that one party where your friend kept disappearing into the bathroom and then coming out with red eyes and an increasingly worse case of the sniffles? Remember when he started making fun of that one woman's clothes and she started crying and then out of the blue, he just grabbed that woman and picked her up and threw her on the floor and started yelling terrible things at her? And remember how the whole party stopped dead and everybody just looked at your friend and you just kind of backed away from him? Remember the look on his face? That was the last time you saw that friend, wasn't it? You maybe heard some stuff about him, but you didn't really care either way; that moment sort of marked the end of an era for you.