These are awesome! I found these at Wal-Mart when I was there shopping for craft supplies.
The top part is a straw drinking cup that can be frozen for up to 4 hours, although we found that just putting in a couple of ice cubes will keep it chilled for a while. Great for taking to the park. But the best part is... the bottom unscrew to hold your favourite little snacks in! Boy, we are going to make good use of these this summer! No more losing our snack containers!
They come in different themes; so far I've seen them in Dora, Cars, Thomas the Tank, and neon green.