Lack of intelligence. It can be said when someone acts inappropriately or says something dumb.
Clown: Guy orders more sushi than he/she can handle
Me: ARE YOU DOOBID?
Verb: The act of mixing on a delectable drink/drank
Dude, dat drank was sew doobid
Mike is doobin up dat drank
dikey and wizzie are at speedway doobiding a slush