I've been to a few room parties that have gotten pretty out of hand (in a fun way).
There was one time where, at SDCC, we ended up heading to some people's house for a AB / Furry party.
A conversation about LSD led to someone leaving for around an hour and coming back with enough for everyone. Most of the people who showed interest at first ended up not wanting to do it, but around eight people dropped that night. I thought the safe alternative was a weed-brownie but it was way stronger than I thought it'd be and I ate two of them.
A few hours later (around 1AM). We have a few people in fursuits and pretty much everyone else is padded. My friend who I knew for almost a year online but met in person for the first time that morning at the convention was one of the fursuiters, also he was one of the people who took the acid. The place was getting was too hot and someone decided that the fursuiters on acid might overheat really easily so he was reduced to wearing only his head. He was tripping rather hard (according to him, an experienced user), and I was in space off the brownies.
We watched a bunch of DBZ movies (one of the few things that everyone likes), but I wasn't really paying attention, and I don't think anyone else was either. The whole place turned into a giant cuddle pile. I spent the whole night cuddling my friend and getting changed by him was the most magical change I've ever had (thanks, weed-brownies).