adj. Inactive, ineffective, in-diddly-etc.
Real citation: "first off, i'd like to raise a virtual glass to my friend rich who FINALLY got the rights to happyrobot.com. you see, he's owned the dot org and the dot net addresses for a while now but has had to deal with non-diddly-squat-doing squatters on the dot net address."
(Oct. 16, 2003, House Arrest, http://www.ashidome.com/blogger/housearrest_link.asp?c=531)
Made-up citation: "Who's better? A non-diddly-squat-doing nun or a post-Janet-Jackson’s-breast priest? Only the Pope knows for sure, and he's not talking."