I'm sat here at work covering both ears in blu-tac, and it's got me wondering -
If you were burglarising a house, and somehow didn't notice that you'd fallen ear first into a load of plasticine or something leaving a perfect impression of your ear, could the rozzers take a cast and prove that you were at least at the scene of the crime?
I guess you could ask the same of a number of body parts. I won't, though.
Side question - to commit the perfect crime, do you think you'd need to learn levitation?