(adj) representing the worst of something. horrible, repulsive, disgusting, annoying, bad idea, indication that if the world was ending in an hour this is the "last" of that item that you would want to be dealing with.
Can also be used as an expression of disgust or hatred.
(noun) the worst, lamest, epitome of a chauncey.
Dude, that chick is soo last.
Last! I don't want to go see "In Her Shoes" again Brendan.
Bros, you know that chauncey Johnny Four Fingers? He's the last.