I don't know what it is about kids and lids, but they just don't work very well together. I've noticed this most with toothpaste. In my house it takes approximately two days for a tube of toothpaste to become permanently separated from it's lid. So I started buying tubes of toothpaste with the flip lids. The only problem is...kids understand how to open a lid, they just can't quite comprehend how to close the lid. So the tube ends up with an ever increasing glob of hardened toothpaste blocking the opening. But my kids don't care. They just keep squeezing as hard as they can until half the tube explodes in the sink. Then they brush, spit and leave everything there to dry. I've never actually witnessed this phenomenon, but the evidence has lead me to this conclusion. My latest solution is to buy the travel size toothpaste. So far it's working. It's still a mess...but a much smaller, travel size mess.