What are some of your memorable childhood pranks?

[Dave W]

When crossing a street at lights or other crossing and a car had to pull up we would look concerned at the front of the car and often point or double back and look again walking or talking or sniggering.
It was then fun to watch as frequently the driver would get out of their car to see what it was that was wrong. Very confused when they couldn't see the non-existant problem.