The worst job I ever had was when I was a customer service agent at a call center whose main client was Netflix. It was waaaay too stressful, to the point where not even a decent pay rate motivated me. Actually most of us there got stressed and I think I lasted 9 months there before quitting :p
Maybe it wasn’t the worst, but when I ran a coffee shop with my girlfriend we were in front of a school. Things were going smooth, but high-schoolers were horrible!! They were having drugs all the time, drinking and disturbing all the order around and the police… Well, they didn’t do much, so we sold the coffee shop and regained our inner peace, lol. I enjoyed what we were doing, but I guess the environment wasn’t that adequate.
My worst job was working at a smoothie place. The hours sucked, the customers were rude, and I hated my boss. He would change the schedule at the last minute, so I would show up for a shift to find that he switched me for someone else… he was a jerk.