Breaking up is hard to do!

Back in April I started using a straw cup. My parents and everyone around me cheered this acomplishment. Next thing I know they are putting my milk in the straw cup expecting me t0 drink it. Well that was May, and I began boycotting the straw cup. So thinking I wasn't ready for it, they gave up.





Now they're up to their tricks again but this time they're playing hard ball. I started out doing pretty good, but then realized that they were not going to give back the bottle. So I am now boycotting whatever comes out of the straw cup, whether it be milk, water or juice. I want my bottle, and I want it now! I don't understand the necessity to give up my bottle. If it serves the same purpose, why can't I have the bottle?