from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Slang A small or worthless amount.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. nothing; nothing whatsoever.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a small worthless amount
Alteration of diddlyshit (influenced by doodly-squat) : diddly (probably from diddle2) + shit, added as an intensive (from shit).(American Heritage® Dictionary of the English Language, Fourth Edition)
The Random House Historical Dictionary of American Slang suggests that this is a derivation of doodly-squat from 1934. (Wiktionary)