(With apologies to Dom, who has already read this..)
Man: Someone has stolen the ball in my mouse.
Me: Have another ball.
Man: Thank you.
A few minutes later -
Man: I can’t work out how to get the ball in this damn thing.
Me: That’s an optical mouse.
Man: Oh.
Me: arghpsjhg.ksjdgnlishgv.knxz;lkgbnzx;kgvbnzxlkfg