Just like on work experience at a local Ford dealership, one particular wag thought it would be funny to send me to stores for some "spark plug gaps", so off I went and told the storeman what was going on and can I have the screw on tops from some spark plugs, I'll bring them back when the pranks over, so I went back and said I've got them, but stores aren't happy opening the boxes for them, here's your spark plug caps, they didn't try it on for the remaining three weeks funnily enough.