Before we go on our walks T always locks the door. Then every time we come back from our walks, he walks straight into the door to see if it's open.

Me: T you always lock the door why do you do that?
T: Sometimes the other T unlocks it.
Me: T ...in nine months that door has NEVER been unlocked, and I've never seen the other T.
T: I'm not crazy.

It was funnier in person