The man card is one of the most important things in a man's life. Possesed almost exlusively by single or unmarried men, to say you have a man card means you're still one of the boys/men; you hang out, do as you wish, spend your money on yourself, play football, drink heavily, and answer to nobody but yourself.
'Poor Rick, its so sad to see him without his man-card. Ever since he got married and had his card revoked, he's just not the same. I could swear he walks with a limp, and I never see him outside of work..'
see also; wuss, pussy whipped, slave, tool