At the end of lunch yesterday I had trouble getting the waiter's attention. Eventually I caught his eye - he was on the other side of the room. He came towards me but I halted him as I only wanted the bill. The gesture I used to indicate this is what I shall call the 'air signature' (as in air guitar and air kiss): that squiggle you make with your hand up in the air as if you're signing a cheque or credit card slip suspended from the ceiling.
Now that we don't have cheques and have gone all chip 'n' pin, I wonder whether this gesture will die out? Perhaps it will continue to be used by a declining number of people who are now over the age of about twenty-five, being gradually replaced by the 'air finger-punch' (four jabs with the pointing finger at an imaginary suspended key pad). Or will it persist long after its referent has disappeared, rather like the handshake (open palm indicating no weapon is being held)?