A friend and I did a dash two decades ago after night out partying. I could have sworn I had a $20 left in my wallet and told my friend I would treat, but when it came time to pay the $15 bill, I only had about two dollars and he had about $1.20 in change. We snuck out.
A couple weeks later (after I got paid), I was feeling awful about it so I put $25 and a note in an envelope addressed to "Manager", and covertly stuck it through the mail slot of the restaurant. But I never went back to eat there for like two years, fearing I would be recognized. Which sucked, because it was a great diner and family restaurant that served decent-enough chow at a good price and was a popular place for gathering after the bar on the weekends.