Urinal Games...

I know parents, who in their attempt to 'potty train' young boys, pour Cheerios into the toilet and tell the young lad "now try and sink them".

A more expensive version of this game has been produced by Yanko Designs (designed by Marcel Neundorfer) called the 'On Target' in which the 'participants' control the video game with... well... a stream of urine.

According to Yanko Designs the reason for doing this is the same as my friends when they use Cheerios at home with their young boys:

Recessed into a urinal is a pressure-sensitive display screen. When the guest uses it, he triggers an interactive game, producing images and sound. The reduced size of the target improves restroom hygiene and saves on cleanings costs - Yanko Designs

Note: Too bad Nintendo didn't invent this... they could have called the "Nintendo Wee".