I have gone to the post office and mailed myself the keys and then gone home and locked myself into a pair of seven inch stilettos. Trapped for 48 hours at least!
It's easy! buy a pair of dog-collar choker-chains (about 20"-24" depending upon the foot and shoe) Then pass the chain under the heel, cross over at the back of the ankle, then padlock the loops at the front. You CANNOT remove the heels until the keys arrive in the mail!
I had to use a pair of 5" heels to get around initially after. It took an entire day before I could walk about flat-footed. I LOVED IT!
And not to mention: THE CHAINS LOOK AWESOME!
http://flickr.com/photos/ultracooltv/216106904/