Forget Kids, I Need This Hand Stamp That Disappears When You've Properly Washed Your Hands gizmodo.com

Photo : Japan Trend ShopEven after singing all six minutes of Queen’s Bohemian Rhapsody, I’m still anxious that I haven’t washed my hands long enough to ensure they’re properly clean.
So I like the idea behind this clever hand stamp for kids that forces them to thoroughly scrub for at least 30 seconds before it completely disappears.
It’s important to keep in mind that the Otetepon Push Stamp should be used as part of a more involved and thorough hand-washing routine.
If you stamp the back of a kid’s hand, there’s a good chance that’s where they’re going to focus the bulk of their scrubbing efforts, which is less effective.
If you’ve got a friend overseas, asking them to buy and ship a couple your away might be a cheaper solution.