OK, pardon my amusement about this, but I just started riding a few weeks ago so the wave thing is kinda new.
Today Im riding to go eat lunch, going on a 2-lane road. In front of me is a lady on a scooter, riding the shoulder letting people pass her on the uphill. Coming towards me in the other lane is a guy on a metric cruiser with a windjammer.
Guy on the cruiser sees me and starts to initiate the wave, and right then I am about to pass the scooter lady. He sees this, and starts pulling back his wave, probably not wanting the scooter lady to think he is waving at her. So I return a wave and when he sees me wave back, he goes full wave again and continues on.
Thought it was pretty funny
