How did The Doobie Brothers get their name?

The band's co-founder Tom Johnston said that the name was coined by a roommate he was living with when the group was in its infancy. John Hartman says that he wasn't involved with choosing the name and didn't know that the term "doobie" meant a marijuana joint until Rosen explained it to him. Everyone in the band agreed that "Doobie Brothers" was a "dumb" or "stupid" name.