Any type of food will make your butt big, but only if you don't eat enough of a balance in your diet.
if you eat a balanced diet, you can eat as much as you like and you won't gain weight.
your body is amazing and you will just poo it all out. :P
it's very hard to eat a balanced diet, don't go thinking you have to eat lots of salads etc. the key is BALANCE. eat a good supply of red meat, oily fish, white fish, nuts, beans, fruit, veg, and starchy foods.
believe it or not, your diet should be mostly starchy foods, bread, pasta etc. you need this for fuel. the more fuel you can get, the more happy your body will be.
make sure you get everything you need, if you are lacking something, then your body will store ingredients in your fat cells in order to try and produce the stuff it is lacking. it's like an emergency store room.