Was exploring an abandoned brewery-turned-nightclub with several other UERers a few years ago, and a local dude who got around on a bike showed up late to the group. When he chained his bike to the fence outside and then vanished, one neighbor noticed and gave the police a call.
They popped in and kept us at bay for a while as they ran our various IDs and unsuccessfully tried to contact the owner. In the end, all of us were free to go elsewhere...all except the dude on the bike, who decided to preach about his rights and generally made the cops' jobs more difficult. He was the only one who got a citation.
Knowing when to shut the hell up goes a long way, both in exploring and in everyday life.

I left a journal that belonged to a long gone homeless teenager in the building because I decided to hide my bag somewhere just incase I got caught. I was too tired to backtrack and left the property without taking the journal. Now I have to go back just to get it so I can learn more about the story of that terrible floor I found it on and of the person that left without it.

Edit 8/12/2020

I geared up and headed back to the location. Security was there this time but I wasn't going to leave those notes in the dark any longer so I decided to evade the guy and go in using red light the entire time. I found the journal where I left it last and went home to read the story of some poor vagabond that was in love with a prison inmate and just wanted to go back to school.... Which is a shame because nearby was a school binder that was urinated on. What terrible sights I encounter.