1 an erection of the penis, Syn. boner, hard-on.
2 A strong drink, a double, esp. a double-bourbon-and-coke.
3 (South Africa) A plastic-cased 3.5-inch floppy disk, as opposed to the more flexable 5.25-inch floppy disk.
1 Oh man, I got a stiffy.
2 Gimme a stiffy and two pints.
3 Have you got a stiffy? I need one to save this file.