Since groin could be both the area of a penis, vagina, both or featureless_crotch... What would a good tag alias be that would accomodate that fact?

groin = crotch?

None. Manually fix it.

If anything, I would say "crotch".

Crotch has been invalidated, and this should too. More specific tags like penis, pussy, perineum, spread_legs, bulge, featureless_crotch, worm's-eye_view, and genital_focus should be used instead.

Crotch_shot is also relevant.

Or, we could revise for characters that wear their below the hips, since "groin" also refers to where the legs meet the hips.

BinaryHedgehog said:
...that wear their below the hips, since...

I think there's a word missing from that.