When in a tavern if the parties thief tries to leave in the middle of the night
Hand another player a blank note asking for a perception check and telling them to say nothing.
Then hand a note to another player asking for a stealth check to DC of other players perception.
Results?
A) Nothing happens and you go interesting
B) Have the first player wake up to something breathing on him as a horrific visage is looking at him(Ask if he screams)