Have your sap lie down on the floor and tell him your going to make him into a birthday cake.

Take a glass, a peice of bread, some matches and some liquid. (beer works well )

Use the glass like a cookie cutter on the slice of bread so that you have a peice of bread the size of the glass.

Place it on the sap's stomach. This works better on fatter people.

Pour some of the liquid on the bread.

Stick the matches in the bread and light them.

Quickly place the glass over the bread.

As the matches burn they use up the air in the glass creating a vacuum and sucking the fat up into the glass. The glass will stay stuck on the sap's stomach for a while. the more matches you use the stronger the vacuum. if you want the glass to come off easy use about 3 matches. if you want it to stay for a while use 5-6