Where Not to put a Hide-a-Key

I went through a phase of locking my keys in my 1986 Honda CRX when I was in my teens. I invested in a Hide-a-Key at Canadian Tire and put it in a place I thought would be a sure-fire hiding place where it was hidden and the magnet latched on like was glued there. Turns out the top of the muffler isn't an ideal spot, all that remained the next time I locked my keys in the car was a black gooey residue where the Hide-a-Key once was.
Favorite Moment: 
The Italian part.