I had a blind friend who had his money organized in his wallet.  He'd
sniff a bill and hand it over.  That smells like a five and this smells
like a ten.  He convinced many that his improved sense of smell let him
detect different odors in the inks.

The best part of the joke was when the sighted people started smelling
the bills and stated that there really was a slight difference and they
had never noticed it before.
 

Mark