Grocery store violation

I was at a grocery store at a non-busy time, and a song came on that I used to love but hadn't heard for many years.  After checking to be sure nobody else was in the aisle with me, I started doing a little dance while I was browsing the clearance items.  After a couple minutes, I heard over the loudspeaker, "Twenty-one in aisle 12.  Twenty-one in aisle 12, please."  I wondered what that could be code for and decided I would go over to aisle 12 and see what was going on.  I looked up in horror and saw that I was in aisle 12!  And I was still the only one in it!  I hadn't spilled anything or stolen anything, so what on earth could a "twenty-one" be?  I'm convinced it must mean, "Turn the hidden security cameras to aisle 12 and have yourself a good laugh!"