Boaz, our Russian Blue, is a key thief.
A couple of weeks ago I left my laptop on overnight to compress some video. In the morning, I found I was missing a function key and several other keys were loose. I figured the cats were roughhousing and ran on my laptop, dislodging keys. "Oh well," I thought to myself, "I'll just cover the keyboard from now on." I found it later on the carpet and reattached it, no problem.
The same thing happened to Cathy's keyboard a few days later. Then, it happened again to me, except this time someone actually moved the cover from the keys first.
Then I witnessed it; I actually saw Boaz walk up to Cathy's laptop, angle his head and pry up a key with his teeth, then run away. As weird as it sounds, my cat steals keys off of my laptop keyboard.