A blend, or portmanteau, of upsetting and unsetteling. It's used to describe the feeling that you can have when you get the creeps but also feel shocked.
Well, The Doctor loses a tonne of friends, and all he does it cry and sop about it, and it makes us cry too.
Now he can just scream this word to the nearest Avacado and get on with his day, or night.
Until he finds another semi attractivefemale human