A Dorito back is a back consisting of huge fucking lats and wide shoulders, making the owners back look like a Dorito. Those with smaller waists may achieve this easier than those with larger ones, however even a person with a chunky waist can have a Dorito back, if the shoulders and lats have good enough proportion.
Did you see the Mr. Olympia?
Fuck yeah dude, Cbum only won cuz of his Dorito back.