I vaguely remember watching an animated movie (or possibly tv show?) when i was a little kid in daycare, which I really enjoyed, but now I can remember almost nothing about it.  This was back in 1989 or 1990 I think.

I’m fairly certain it involved a group of people (or possibly human-like creatures) living underground, or maybe being trapped underground.  The only scene I remember is this group of people coming across someone they didn’t know who I guess ended up there by accident, not being sure whether this newcomer was a boy or girl, and one of the girls in the group checking under the loincloth he was wearing to find out he was, in fact, a boy.  I probably only remember this scene because every kid in my daycare was *scandalized* lol

I don’t expect to ever track down this movie with so little to go on, especially since my memory is notoriously poor and I might be remembering details incorrectly after so many years, but it’s worth a try.