Years ago, I worked (briefly) in a cream cheese factory where one of my lovely jobs was to cart 70 lb. boxes of hot cream cheese that didn't settle properly, up a dozen steal stairs and pour it back in to these huge boiling pots to be processed again.
If that wasn't bad enough, another part of the job entailed standing on line with these plastic gloves on, and wrap the boiling hot cheese before it settled. If you didn't wear the gloves you instantly burnt the shit out of your hands, but if you DID wear the gloves, they heated your hands up to twice the temperature of just "burnt", but in a slower fashion. Not only that, but the tables were just slightly too low and after two minutes, I thought my back was going to break.
They were shocked when I came back after my morning break, because I guess most people just walked out and never came back.
I stayed one full week.
It's a toss-up between that and another job which was at the opposite end of the spectrum. It was in a chicken processing factory where my job entailed standing in a room that was at 28 degrees F with 40 other people, feeling for small bones in half-frozen chicken breasts. After 2 mintues, your fingers are completely frozen and you can't feel a damn thing anyway, and you realize that you only have another 7 hours and 58 mintues to go.
And if you're foolish enough to try and warm up your hands under warm water, then pain takes on new meaning as it feels as though your fingers are burning in the flames of hell, and you scream and yell like a donkey as you slip slide your way back to the line. There was one guy standing next to me and he says "this is really hitting the bottom of the barrell." Well, we both started laughing and laughing and laughing, and then we walked out right then and there and never went back.