Something that really pisses me off:
When I go to a restaurant, and the food is good enough and plentiful enough to take home, so I ask for and get a little box to take it home in--
--which I then forget about and leave in the booth, and when I remember, it's too late because they've already bussed the table. >:( >:( >:(
...And to top it off, I think I may have stiffed the waitperson on the tip because I am incapable of doing math in my head. :(