It can take on two meanings. It can be a command, dictating one's gaysexual boyfriend to lubricate one's asshole, or a state-of-being, such as in the example shown below.
Carl, for fuck's sake, just lumb!
2. Describing a object as useless and unnesessary.
3. Describing a place where there's nothing to do, that's useless and that seems unnesessary.
Mark Brownstein: Yeah, but so is Aaron Murray's hometown.