This is my 10 year old's cake:
The fries are browned slices of pound cake. The "ketchup" is white icing mixed with red and a little brown food coloring. The hot dog is a pound cake and twinkies and directions are found HERE and HERE.
This is my 8 year old's cake:
My younger son wanted a dog. HERE are the best directions that I could find. The results were not perfect but certainly fun and pretty easy to make! I suggest before you begin the process, you make a trip to the dollar store for supplies. It is far cheaper than Michael's or the grocery store. This cake was pretty cheap as it only requires one box cake and two cans of frosting. The expensive part was having to buy the frosting tip for the "hair". Michael's had a 50% off printable coupon so it was not too pricey (about $5). Don't forget the pan for display at the dollar store. Buy two for each cake for extra support in transportation.