Means you're too late. Like if a guy likes you and then another one asks you out before him, you say to the first guy, "sorry, day late and a dollar short." So basically, you waited and screwed yourself over.
Guy: Hey, will you go out with me?
Girl: Sorry, day late and a dollar short... Guy 2 just asked me out yesterday.
Girl: Sorry, day late and a dollar short... Guy 2 just asked me out yesterday.
by Pretty Emily October 25, 2004
An expression used by those who are with incredible stupidity and of a state of retardation that pairs well with their receding and grotesque hairline
by 3idbwkabsi3 April 16, 2017