Dishwasher Instructions

Alright listen up, buttercup. The "joke" here compares a dishwasher, you know, the machine that cleans your plates because you are too lazy to do it yourself, to a woman. The punchline implies that you can get a dishwasher (or a woman, according to this prehistoric knuckle-dragger) to work by smacking her and bossing her around. It's funny because it's WRONG and OFFENSIVE. But you wouldn't know, would you?