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.
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.