How to lose a touch of belly fat in VERY little time?

I’m going to be wearing a bikini tomorrow, and I’m definitely not overweight, just a little bump and a bit of a gut, but I’d like to just look a touch skinnier. I know people will say it’s stupid for a 13 year old but just a touch. Clearly I can’t drive and get a product, so what kind of exercises can I do to (temporarily) get rid of a little bit of belly fat? Anything other than sit-ups and crunches?