Weasel

Q: What do you call someone who takes your bike out for a ride without permission then acts all buddy buddy with you?

A: A weasel.

I left my bike in the storeroom of my workplace and a weasel took it out for a spin in the courtyard. When I returned, the front tire was flat, the solenoid for the cyclometer was pushed inwards and the rear light was mounted backwards.
From the looks of it, the bike took a hit on the right side that caused all the accessories to move out of place.
That weasel still has the cheek to tell me the bike was fine when he returned it back to its place.
Will be locking my bike in future.