How can i sneak out a bottle of alcohol, without my parents noticing?

I’m going to a party, and i promised to bring some booze to the pregame. But the thing is that my parents are very controlling about hard alcohol, so i wont be able to just take it outside. I can’t take a bag or some kind of bottle bc they’ll find it weird why i would take it with me to a party. It is a small 33cl bottle. Does anyone have a better idea?