This happened the other week at the variety goods shop I work at.
It's now the christmas season which means I start work an hour earlier than usual, at 8 instead of 9. We still open at the usual 9:30. It's nice though because I can actually get an hour of work done without being bothered by customers... or so I thought.
Our shop has just been remodeled and we no longer have the metal barrier thing that goes up and down. Instead now we just have two glass doors. Because of this sometimes customers see me counting the tills and assume we're open, they usually figure it out when they find the door locked or I direct them to the opening times sign that is just to the left (it's in a weird spot so I don't blame them for not seeing it).
It's around 9am, me and the new girl are working downstairs while the manager is upstairs doing paperwork or something. I go to the back room to get some stock and when I come back around 10 elderly customers are milling around the store. New girl comes up to me and asks how we turn the music on, regular employees don't control the music and they also can't unlock the front door. Music is usually turned on before we open so I figure we didn't just start opening at 9 for christmas. I call my manager and she rushes downstairs.
We had to awkwardly shoo them all out (which they were all confused and upset by) and my manager checked the lock. She unlocked the top and bottom locks earlier to make it easier to open but the middle lock was still locked. One of these customers were so eager to get their shopping done they forcibly broke the lock by pulling the front door open and just let everyone else in.
You'd think the opening sign, fact that there was no music, no visible staff downstairs and the fact that they had to forcibly open the door would have tipped them off that we're not open but I guess not.