A toilet or bathroom designed or used specifically or mostly for males. Usually adjacent to, or near, the garage, workshop, games room. Likely equipped with a urinal, large capacity toilet, magazine rack, and possibly a shower stall (not a bathtub) or tv, music, or speakers.
I needed some time away from the wife, so I went to have a sit-down and read in the man can.
Any 24 Oz can of beer, usually domestic, not to be confused with a "tall boy", a 16 oz can of beer. A man can is bigger in both diameter and height, and a tall boy is the diameter of a normal 12 oz can but taller.
A man can is any 24 oz can of budeweiser, miller lite, bud light, etc.