This is actually old technology brought into the 21st century. Many companies over the years have developed "toilet targets" primarily intended for young boys in the potty training stage of life. Some were floating battleships that would sink when hit. Others were stickers that would change color when **ahem** urinated upon.
Adults soon realized the novelty of it all and party hosts in particular would replace the Ty-D-bol man
with these targets.
Now if they could only do something for party "poopers".