Mine came from back in the days when you didn't loose your job instantly for horseplay. A guy, 5'4" maybe 120 lbs, at work had a habit of dropping bolts, washers, rocks, ect into peoples pockets when he was near them. I warned him if i caught him i would put him in the 55gal garbage can in the shop. While having him upside down trying to push him in head first some pipefitters saw us and gave me my nickname. Since im 6'2" and weight 275 lbs i'm kinda built like a wrestler. Some of the new guys in the past two years refer to me as Shrek but i already use Mankind for everything so....