Wave to them when they beep. That will upset their day.
They will be wondering why the wave. Going 'round the twist, "Do I know that person?" Not getting the "bird" but a wave? "Why?"
One lady would blow a kiss.
The impatient beeper would take off, "That idiot's beyond help. I was being rude to her and she blows me a kiss? NUTS"
Cheers