When a guy's butt crack is visible when he bends over. Related to the term plummer's crack. Apparently many plummers butt cracks have been visible while working in client's homes.
Man1: Dude, cover that up!
Man2: what?
Man1: your ass crack, you're plummering something fierce.
12 step recovery jargon referring to someone new who talks about how great life is, now that they'resober. Usually meaning that the person is out of touch with reality.
The new guy seems pretty happy for a dude who has no job, no money and no family. He must be on a pink cloud.