Who makes that FAKE pool water urine detector?

Many people have probably heard of a chemical that you put in your pool that makes the water change color when someone urinates in there. Such a chemical does not exist.

HOWEVER, when I was younger, my old neighbors had a pool, and they had some tablets that you could throw in the water and they dissolved and turned the water bright/neon yellow. It was meant to be a prank. Like you, would quickly throw one of the tablets into the pool next to someone when they weren't looking and then it would dissolve really quickly and turn the water a bright/neon yellow.

You could build up the joke before hand by telling people before they get in the pool, that you have that urine detector chemical in your pool, or just wait until after you throw in the tablet. In any case, even though it was a yellow color, it was not meant to look like actual urine, because no one's urine looks that color.

I was just wondering if anyone has seen this stuff before? It was a long time ago (mid 90's), but If anyone knows about this stuff, and can tell me who makes it or where to buy it, I'd really appreciate it. Thanks.