Ahhh, nothing like the holidays to remind me whose face I'd like to take a giant piss on. PPShots produces Adhesive Photo Protectors--clear toilet sticker designed to house and keep intact photos stuck on the inside of your toilet bowl for weeks. For what purpose? For the highly satisfying figurative purpose of providing your least favorite friend, family member, or celebrity with an unsolicited, but badly needed, golden shower. Every single time you need to whizz.
Suggested as gag gifts, wedding gifts, birthday gifts, bachelor and bachelorette favors, target practice for potty trainees, and, my favorite, small implements of revenge, PPShots Protectors are made of water-resistant materials and backed with an adhesive tough enough to withstand flushing and bodily waste impact for a handful of fortnights. At least long enough for you relieve your aggressions in conjunction with your bladder.
Disclaimer: PPShots advises strongly against using their Photo Protector to house the images of professional athletes and politicians you hold in low esteem. They even provide links here to many of these people's images in an effort to show you who you should avoid introducing to your urine stream. Call it anti-inspiration.
I myself would never try to dissuade you from peeing on anyone. However, if you want to avoid animosity from people of a different opinion who might use your bathroom, I would recommend sticking with photos of people everyone hates, such as Satan and Snuggle the fabric softener bear.