that's a dick move... kinda like opening your door when one is about to filter past you... it's just ignorance. Why fuck with someone's bike? I can see it from ignorant fuckers who don't ride/can't ride, but from a fellow rider? complete bullshit. I'm of 2 minds about the issue, if for some reason the parking lot isn't a viable option, I can understand using empty sidewalk space, but honestly, the majority of the time, the parking lot is perfectly fine. now how do you feel about double parking with other bikes (people you don't know)? if I find a bike parked single, I will sometimes park in the same spot if it looks like an easy/convenient thing to do, and if not, I park in such a way that someone else on a bike can park in my spot with me. (diagonal to the lines, towards the front of the space) this seems especially effective when parking on the street against a curb.