When you hold down the shift key to use "!" (or any other thing you need the shif to use)multiple times and you "slip" on the last one.
by flipflopsandsocks March 10, 2008
When you try to press the ! key on your computer a billion times, and it looks something like this: !!!!!!1111
Oh Man!!!!!11 i just sent message on facebook and accidentally shift-slipped, they're all goin' to think I'm a noob!!!!!111
by S_BIRKO September 04, 2009