There's an even sneakier form of urinal advertisement out there. Since my readers of the female persuasion
may be unfamiliar with the urinal hardware itself, I'll explain in deliberate detail:
I first encountered such urine-soaked commercialism at the AMC 1000 theater in San Francisco. Just before our movie was starting, I ducked into the men's room to prepare for an uninterrupted film-watching experience. The urinals here are the kind mounted on the wall at just below waist level, not the shoulder-to-floor variety. Actually, they're designed quite well, with the pointed front of the bowl jutting forward in the middle, so that the last few drops that drip when you tap-tap don't end up on the floor, as they do with traditional flat-faced urinals. Also, they've got the IR-based auto-flushing systems, so your hands stay cleaner (and it's always piss-free when you walk up, even if the last guy was lazy).
Urinals often house urinal cakes, little pucks which help it smell like something other than just piss. In order keep the cakes from getting flushed down with the rest of it, perforated triangular plastic cards are placed in the base of each urinal. These also help the urinal from getting clogged and overflowing in case some idiot can't tell the urinal from the trash can.
This particular triangle-thingy was red, and as I unsheathed my package I noticed what looked like some kind of black powder or something smeared across the top of it. I started my stream, and went to wash off the black stuff with it. I could never have been prepared for what happened next: The blackness vanished with the heat of the urine stream revealing the advertising logo of a local modern rock radio station. I started chuckling a little bit, getting a kick out of pissing on the Live 105 logo, and watching the black bar reappear when I aimed elsewhere and disappear again when I returned. Yeah, I'm easily amused.
I finished, tap-tapped, zipped up and went to wash my hands (where they again used IR to prevent you from having to touch a grimy faucet or leave the water running) and exited the restroom. As soon as I found one of my male friends I told him he had to go in and piss in the urinal. He entered confused, but exited laughing just as I had minutes before. We exchanged "that's the coolest thing ever" and tried (ineffectively) to explain it to the women in our party until the house lights dimmed and the previews began.
Really, this idea involved no new technology; we all know hypercolor has been around for some time. They printed a white logo on a plastic sheet and covered it with a black plastic strip that turns clear with heat, and stuck it in a pisser, and it puts bread on the table for someone out there.