I worked in a psychology lab for a summer during college, literally running rats through mazes. The rats had been used for a new neurosurgery technique, and I was supposed to run the mazes to ensure they had nothing wrong with their spacial reasoning skills or memory before they were euthanized and the surgical areas were inspected more thoroughly. The surgery was the primary experiment - I was just an underling to the graduate student who got fortunate enough to be allowed to use the rats for a secondary spacial reasoning experiment for a few months. This graduate student was fairly new to the US and new to our university, but he acted like he ran the whole lab.
The whole point of the experiment was for the rats to learn. The natural consequence of this is that the rats started doing the mazes faster and faster as the weeks went on. This meant I started out with 10-to-11-hour days at the beginning, while all the rats took forever, and ended up doing 2-to-3-hour days (plus some computer time) by the end of the experiment once they all learned how to get through the maze on the first go. I was explicitly told that I would be paid for 8-hour days for the duration of the experiment since it would all even out in the end anyway. It sucked at first, of course, but by two months in I was enjoying being able to sleep in a bit, run the experiments, hang around the lab for an hour or two to input data, and then head home by mid-afternoon.
Except then my boss (who was never actually in the lab) started showing up at 4:59 and being mad at me because I wasn't there. I literally had nothing else I could do - I cleaned, I ran the experiment, I took care of the rats, I did the data entry, and I did what little data analysis I could, but I wasn't qualified to do anything else even if there had been something else to do.
The last week involved throwing the rats into a kiddie pool full of watery paint (water maze experiment) - which involved a full week of scrubbing out the pool by hand first, because the previous researcher had been using different-colored water. I also broke two pumps trying to empty the pool because it was so full of rat hair and droppings
Oh, and it was a small, windowless, unventilated room, with extremely bright and hot lights. I would have sprung for the $10 to buy a new kiddie pool and throw the old one out (it was literally the kind you can get at Wal-Mart), but it wasn't up to me
Anyway, after working my tail off and getting yelled at for it, I was seriously ready to quit my job two days before I was scheduled to leave. Now-DH's suggestion was "If I were working a job I didn't like for a boss I didn't respect to earn money I didn't need, I'd tell him to go fly a kite." I stuck out the last few days, but it was tough. My boss's final comment to me? "I should have known not to hire an undergrad to do this; they always #@$@ things up."