I live in Colorado and it seems to be well known you get your ass kicked if you sit on somebodies bike. Have never seen it happen to mine or any others bike, even the 1973 Harley show bike.
There was that time though I told a girl I had a 500lb vibrator parked outside (Harley Sporster) and she asked me to prove it. Imagine a sporster with straight pipes and the throttle pinned right outside a bars front door. I think most of the bar was out there when she had an orgasm