When you fill a blunt with mostly weed but one small part of it, anywhere in the blunt, is filled with salvia. While smoking down the blunt one person reaches the salvia and gets way more fucked up than everyone else.
1: Hey guys who's down to play some blunt roulette?
2: No way man! Last time I played, the dragon from Lord of the Rings burnt down my house.
1: So you lost? That's the fun in blunt roulette!