How can I get a flat tummy in 5 or less days?

I am going to a wedding! I am 12 , 5*2 and 112 pounds. How can i tone and flatten my belly in less then 5 days?
HELP!
OK I dont think you get it. Im not trying to lose weight im just trying to tone up my belly and maybe lose a bit of the fat.
Would it help if i stopped eating dessert?