A scatalogical sex move wherein one partner assumes the lobster position by squatting over another's open mouth, makes claw-motions with their hands, and defecates into their partner's mouth. It is usually courteous to return the favor.
An alternate but rarely used form known as the Squat Rock Lobster exists, where the lobster-partner sticks small rocks (pebble-sized) up their anus beforehand to pelt their partner with as they shit. This satisfies both scat fetishes as well as pain/torture fetishes, and as a double bonus goes great with the B-52s' single Rock Lobster.
Mark: So, did you hook up with Jessica last night?
Kevin: Yeah man. I gave her the ol' Squat Lobster as a finisher.
Mark: Didn't...you go out for Mexican last night?
Kevin: That may be why she hasn't called back.