Some crazy ritual the LSD cult uses to ensure loyalty of it's members. Basically it just means eating a shitload of pure LSD crystal powder so you supposedly can " see the light ", but really this is just so you stay devoted and don't rat. people who've been printed are willing to do life in the pen to protect their acid. pretty creepy shit.
go down to telegraph ave or 13th st sometime. you'll see what i'm talking about.