After cleaning up yet another puddle on the floor from a leaky sippy cup, I've decided to turn to you ladies for some help. I have both a Nuby and a Munchkin straw sippy cup, they both have a plastic piece that slides over the straw for travel and they BOTH leak. (out of the top part by the straw, not the sides for the couple of times I did indeed not screw the top on properly...) Does anyone use a straw sippy cup that doesn't leak? Please let me know! When I have DD in the car for long rides a sippy cup with water keeps her quiet but then she's soaking wet when I take her out. The simple things in life, ahhhh!!!