The rats (these are particularly thick rats) have taken to running in the wheel in their cage. All fine and good, except the damn thing squeaks. So I put a little olive oil on the metal axle. Aaah, silent. However, I seem to have completely confused the rats - the coefficient of friction is now noticably less, and their usual trick of standing up in the wheel now causes it to swing from side to side as they overcorrect for the swinging - I was nearly in tears with laughter this morning! Poor, daft rats!
Thank god it's Friday.