Bike helmet that smells bad when it's cracked

This is cool. A bike helmet made with lots of little capsules of some stuff that smells bad. If a kid drops his helmet, and it cracks, he'll know because of the smell (and not want to put it back on).

And I guess if you find your kid lying on the sidewalk next to his bike, and the helmet smells bad, you know he's had quite a hit on the head.