Season ground beef as desired. Divide into 12 small patties. Flatten ground beef patties to fit larger than size of roll (patty will shrink when cooked.)
Dice onion into small pieces and sauté in heavy skillet with butter over medium heat until translucent.
Place patties over onions and press patties down firmly with spatula; this allows the onions to cook into patties.
Fry over medium heat until done.
Pull apart rolls in each package. Slice roll in half; place a patty in between each roll, add either tomato or pineapple, and serve.
To make teeth or fangs, start by cutting cheese slices into triangular pieces. Lay the cheese over the hamburger patty with their sides hanging over. If you like more cheese, make more teeth!
Using toothpicks, secure three pimento stuffed green olives for eyes, and add pineapple ears onto the top roll.
If you would like to add legs, cut 4 squares of cheese from a cheese block and secure with toothpicks.