I found it rather odd when learning to use @nakeds that there was no "buttocks" entry. It seems like a key body part is missing from all Sindome residents! Maybe they're surgically removed as part of the immigration process? Joking aside, this seems like an oversight. I suppose you could describe the butt as part of the back, except there are certainly outfits and circumstances that would expose one's back without exposing lower than the waist. I've seen some include such a description in the groin slot, but a butt is definitely not part of the groin by any stretch of the definition (look up "groin," a key part of the definition is "front"), and there could very well be situations where one would be covered and the other would not.
So how about it? Can Withmorians get their butts back? Or are they still held up in customs?