Don't know who said it, but the full quote:

(Luke won a game of poker on a bluff)
Dragline: Nothin'. A handful of nothin'. You stupid mullet head. He beat you with nothin'. Just like today when he kept comin' back at me - with nothin'.
Luke: Yeah, well, sometimes nothin' can be a real cool hand.

Other quotes from the movie here:
http://www.imdb.com/title/tt0061512/quotes

Robert