Shame on you old boy you have forgotten the no1 whistle . The wolf whistle its now illegal .
It might not be PC, and I don't think I have done it since I was a teenager, but it is interesting to see the reaction of a pretty girl who has been wolf whistled. She may put on a haughty or annoyed expression for a moment but she perks up, thrusts out her breasts, and walks on in a proud manner. Hard to define but I'm sure you all know what I mean. The girl who didn't get any wolf whistles was always jealous of those who did.