As I'm walking all of a sudden I notice that J Lo was a few feet from me with cameras on her, clearly in the middle of a scene they were actively filming. I play it cool and walk into the bodega, where the film monitors were setup and people were watching the live feed. Some guy -- I read him as the DP -- goes "hey nice work, you're background?" to which I respond "oh, no man, I'm just buying something". They shut the whole scene down, because clearly I had no contract and ruined the shot, and as I walk out of the bodega J Lo is just looking at me smiling.
Some PA totally got fired that day.