Noun
(vulgar, slang) An erection of the penis.
Fred's got a bulge in his pants - you can tell that he's got a stiffy.
(South Africa) A computer floppy disk of the kind supplied in a stiff plastic outer shell.
Never leave home without a spare stiffy disc in your bag.
(slang) An extended magazine of a gun.
Source: en.wiktionary.orgStiffy was one of those girls who enjoy in equal quantities the gall of an army mule and the calm insouciance of a fish on a slab of ice. P. G. Wodehouse