Grass-eater

A blonde was driving along in her car one day, when she noticed a man at the side of the road, eating grass. She pulled over and asked him "Why are you eating the grass?" The man replied, "I'm too poor to afford any food, so I have to eat the grass to stay alive." The blonde said to him, "Don't worry, you can come back to my house and I'll give you food." The man, overjoyed, asked the blonde, "But why are you helping me?" She replied, "Well, I like cows." The man, who didn't think he'd heard her properly, repeated the question. "Why do you want to help me?" She said "Because cows eat grass, so you must be a cow."