In high school, someone drew one of them on the dry-erase board; it was behind a pull-down shade. When the teacher lifted up the shade, he saw the lovely drawing on the board, and he got all flustered.
At the time, we had a wheel-in television, which was connected to an outlet, so when he decided to reprimand the hooligans, he stomped over the television's wires, tripped, and screamed, "WHO KEEPS DRAWING THESE DAMNED PENISES ON THE BOARD?!!?"