diddly-squat

Etymology
The Random House Historical Dictionary of American Slang suggests that this is a variation of from 1934, probably from American slang  +, used in the sense of defecating. Doodly-squat was originally the more common form, but overtook it in the early 1980s, and is now an order of magnitude more common in print.

Noun

 * 1)  Nothing; nothing whatsoever.