The bank robber enters the bank with his gun drawn in plain sight.
He walks to the middle of the lobby, pauses for a few seconds, turns around a couple of times, and then approaches a teller.
Then scratching his temple with the gun barrel, he says to the teller, "Do you ever enter a room and forget why?"
A bunch of ellipses, a cylinder, and some lines are hanging around together talking:
The ellipses, “Hey, we’re leaves!”
The long cylinder, “And I’m a trunk.”
The lines, “I guess we’re branches.”
They arrange themselves accordingly. Euclid comes along, sits down next to the shapes, and asks what they are.
The shapes respond, “Gee, I’m a tree!”