Like, "Dick-tsundre" or something. Could be a term in english or japanese or something.
Generally a gynomorph who is somewhat troubled by their penis in day to day life, going to extents to hide it under their clothing via various means, but giving into lust now and then.

"Stupid penis why won't you go down, baka."
"Dammit, why an erection now *whines*"

There is the unwanted_erection tag. You can combine that with any sex or gender tag you want.

Yeah, I guess that works for searching... hm.
perhaps I'll also throw in tags like
Enhibitionism
and cum_in_clothing cum_through_clothing
etc