Construction worker on the 5th floor of a building needs a handsaw. So he spots another worker on the ground and yells down at him, but he can't hear him.
So the worker on the 5th floor tries sign language. He points to his eye meaning "I", points to his knee meaning "need", then moves his hand back and forth in a handsaw motion.
The man on the ground floor nods his head, pulls down his pants, whips out his chop and starts masturbating.
The worker on the 5th floor gets so pissed off he runs down to the ground floor and says, "What the hell is your problem?!! I said I needed a handsaw!"
The other guy says, "I knew that! I was just trying to tell you - I'm coming!"