An expression used when the ordinary damnit just won't do or has already been used. If one has already used the word Damnit and is in need of a new curse word then then 25 seconds later, one must succumb to the word Double Damnit. Traditionaly used in the game of golf when one thinks that nobody is around because one is too embarassed to admit that it truely is a dumb curse word.
(Tee's off a slice) Damnit!!!! (Does it again) Double Damnit!!