There was an old interview with Alternative Press that came out as they were finishing up recording TOYPAJ where they talked about their drug use. At the time they smoked heaps, did a lot of ecstasy, and Mark told the story about how he was drugged with acid that ended up inspiring Fighting the Gravity. Not sure if they mentioned anything else, it's been a long while.
I know ages ago I had posted the relevant parts from it because at the time everyone on here was young and kept saying there was no way any of them would ever do drugs because drugs are bad. I'm way too lazy to go back that far in my post history, but if anyone else wants to do some digging it was probably about a decade ago. Wow I've lurked around here a long ass time.