Worst: (While in college for the 1st degree)
#1 - Pig Barn - had to be there before the sun was up and litterally scrape and wash the crap out of the barn. (Concrete floors inside and out) There is nothing like the July sun coming up and hitting the dew on top of pig crap to open your nostrils. My roomates would not let me enter the house with my clothes on or wash my clothes at home, so I had to strip down to my underware on the porch, go inside to shower, then go to a laundry mat to wash daily.
#2 - Dairy production plant - Not quite as early as dairy farmers, we only had to be at work at 4:30. Washing the machines with water at boiling temp (hose was 1/4 inch thick). Even wearing ear protection, I could not hear people at normal levels for a hour after work. And making cheese, for those of you who like cheese, I will not go into the process.
Mind you, for both of these jobs, I was a 19y/o male with many older friends in Frat's. At least a third of the time, I never went to sleep before going to work.
Best Job: (While in college for the second degree)
ABG/EKG tech for a Level I Trauma center - carry code and trauma pagers covering the entire hospital. Being one of eight people around a body in the middle of a trauma and sticking and hitting the artery and having the head of trauma say "Nice", walking on clouds is nice.