Because they lead a doobie-us lifestyle.
Doobie doobie doobah
The I. C. U.
...and finds himself in hell. Walking around, he runs into the devil.
Devil: Why are you so sad?
Guy: Why do you think? I'm in hell.
Devil: Hell's not so bad. We actually have a lot of fun down here. You a drinkin' man?
Guy: Sure, I love to drink.
Devil: Well you're gonna love Mondays then. On Mondays, all we do is drink. Whiskey, tequila, Guinness, wine coolers, Diet Coke. We drink until we throw up and then we drink some more.
Guy: Gee, that sounds great.
Devil: You a smoker?
Guy: You better believe it.
Devil: All right! You're gonna love Tuesdays. We get the finest cigars from around the world and smoke our friggin' lungs out. If you get cancer, it's okay -- you're already dead.
Guy: Golly!
Devil: I bet you like to gamble, too.
Guy: Yes, as a matter of fact I do.
Devil: Good, because Wednesday is gambling day. Craps, blackjack, horse races, you name it. You like to do drugs?
Guy: Yes, I love to do drugs. You don't mean...?
Devil: That's right! Thursday is drug day. Help yourself to a great big bowl of crack. Smoke a doobie the size of the Titanic. You can do all the drugs you want, and you'll never die -- you're already dead.
Guy: Neat! I never realized hell was such a happenin' place!
Devil: You gay?
Guy: No.
Devil: Oh, you're gonna hate Fridays
