This soap is meant for kids, but looks like tons of fun- “SquidSoap works by applying a small ink mark on a person’s hand when they press the pump to dispense the soap. The ink is designed to wash off after the hands are washed for about 15-20 seconds, which is the time recommended by most doctors. SquidSoap is lots of fun for kids, since they love to get marked. It makes handwashing more like a game. Also, the very stretchable squid toy is a blast to play with and will provide hours of entertainment.” [via] – Link.
Timed, washable soap/ink for kids – SquidSoap