Kristin’s improvised her own spill-proof drink container:
While eating out at a restaurant, milk is often served in plastic cartons. On several occasions, our twin boys have spilled the milk by tipping the carton too high up too fast. The last time out, I thought to take a plastic knife, slice a very thin hole in the protective cover (the one under the cap) and slide a straw into that thin hole. Whaaaaa laaaa! It worked!!! No spilling at all!