teenage son clothing issue

[SAJmum]

We have an 14yo son and an 11yo daughter.
Husband works abroad 75% of the time.
Recently found girls pants in sons bedroom,
(he hasn't got a girlfriend to my knowledge)
Don't wish to discuss with my female friends,
or with DH because he is rather strict.
Any suggestions, or should I just ignore this phase?
Leave pants at back of his sock drawer and forget?
Put pants into the wash (they are yucky) and return?
Ask him about them (probably cause red faced row)?

By yucky, do you mean semen-stained?

In which case, I'd wash and return to back of drawer. Don't embarrass your DS by asking about wanking fantasies and his he acquired the props. Bad enough that you washed them and said nothing at all.

You might like to put a box of tissues in his room too.

I guessed that's what he's doing, but really didn't want to think about it.
Thanks for comment, which seems like a non-confrontational option.
I might put a matching box of tissues and reed diffuser in his room.