This joke at made me laugh

Sticky Mouse
By Peter Seed
I once found a colleague with his mouse on its back, ball compartment open, poking a tube of superglue into the inside. I naturally asked him what he was doing.

"I'm gluing this washer/o-ring thingy back onto the roller - it has slipped and my mouse only works intermittently".

I'd never seen such a washer/o-ring thingy, but sure enough, on each of the rollers, at the point where the ball contacted them was a shiny black ring, about a millimetre thick and two and a half wide, looking for all the world like a tiny grommet or o-ring. He was trying to glue the crud he'd picked up off his desk, polished to a high sheen by constant movement.