Aspirin

A bloke wakes up in the middle of the night and rolls over and shoves an aspirin down his wife's throat.

All of a sudden she wakes up and yells, "What the hell are you doing?"

"Just giving you an aspirin for your headache." The bloke answered.

"But I ain't got a headache," she yelled back.

"Good then, lets have sex!" said the bloke.