Oh god, I'm going to have to be the Old Trans explaining why everyone else's guesses on this one are wrong, lmao.
Back In The Day, before prosthetic soft penises ('packers') were widely available and cheap, a common substitute was to take a condom and fill it with hair gel. I never did it, but it was a tip around the time I came out in the mid 00s (although by then it was already starting to fade out in favor of silicone packers used today, it was mostly an affordability thing at that point). These weren't for sex, it's just to have something in your pants during your normal day that's penis shaped.