One of my best ones is I was working at a large supermarket store when I was 19yrs old, on the Deli counter. I booked off a day 4 weeks in advance because I had a ticket to a gig for my birthday, and the day before I was supposed to go I was told I couldn't have it off because there was no one available to work the solo 4:30-8:30 shift (I had to travel an hour to the gig so I'd miss it completely with this shift). I argued but didn't win and they made me work it.
So I started my 4:30 shift the next day and just began all of my “closing up duties” and managed to close the entire deli bar down by 5:30. I then just left and went to the gig and no one ever noticed. (And I still got paid for the 4 hours )