How to get a flat stomach in a week!?

Hey all well prom is in a week and i already have a decent looking dress…its nothin fancy un4tunatly but its still cute…everything is cool exept for my stomach..it not like ‘BIG’..but it showz on the dress :s sooo i was jus wondring if there was anythin i can do to get rid of it..oh tried dietin n push upz by the way lol
Thankz for your time
Take care