Wad is a
slang term which describes:
1. A bundle of money, usually of the paper "folding stuff" variety.
2. A male's ejaculate, especially in the coarse usage "to shoot one's wad".
The origin of these usages is from the military, where the paper stuffing of a cartridge shell is known as the wad or wadding. In the second usage, it bears noting that the wadding is expelled when the cartridge is shot.
3. An exceedingly stupid person.