We'd just lost several employees (some fired with good reason, some quit) and I was working till 11 at night every night, often over that time. This week I had just pulled 8 days in a row with one day off and was 2 days into the next work stretch. A customer complained about me because I seemed "huffy" when telling another customer that there was another open register and she didn't have to wait behind 3 people. At that point I just started crying because I had no idea what was going on and I was exhausted.