I didn't stop to greet some customers as I walked in with a cane for the third week in a row due to nerve damage.
I wasn't on the clock, we didn't have a uniform, no name tag, nobody would even know I work there until I put my shit on after I clock in.
By that time I had made it a habit of recording every interaction with management, so I just pulled out my phone, hit the record button, and asked "so to be clear, are you officially reprimanding me for NOT doing work off the clock?" and that immediately shut him up.
Managers get awfully pensive when they have recording devices capturing them.