Interestingly enough, Spider-Man’s origin story does not specifically mention any changes to his genitals. We do know that he grew much stronger overall (possibly relevant) and that he can stick to things (definitely relevant). It’s not only his hands and feet that can stick to walls, it’s his entire body (we’ve seen Spidey prevent his mask from being pulled off by making his face sticky). Essentially, this means he can lift large objects, like a briefcase or some lumber, with his super-strong penis. This has rarely come up in the comic.