T.A.
We had the same exact problem. I think I own every brand of sippy cup! The ones that did the trick for us - the supper cheap disposable types "The first years". I bought them at Albertson's on the top shelf. It comes with 4 cups and they are made so you can throw them away if needed, like cheap Tupperware. They are not my favorite simply because if he tosses it aside the lid will pop off, but they work for him.