One time I parked in chinatown at 5:30 am on a Sunday in a spot that has free parking on Sunday. At 2:00 pm when I left there was a protest, with a full band, bleachers, and a dancing dragon around my car. Along with a temporary no parking sign, and a ticket. That sign was definitely not there in the morning, but I had no proof, so I just paid it.

Interesting side note, I recently had an Uber driver who worked for the PPA.