It seems to me that we have general tags for various realms of interaction, such as vaginal, anal, and oral, but we don't have anything relating to stuff involving the penis.

I think we ought to have a penile tag for any sort of activity involving the penis.

Right now there's no way to search for images which may include a penis but which don't involve interaction with said penis. Or to search only for images where the penis is being involved.

I'm not quite sure how this has been overlooked for so long, but it occurred to me when I was attempting to perform some searches and found the available options lacking.