Current/former Nine Inch Nails fans (hence, the "NIN" part of "ninnies") who originally met through the Net (old-school ninnies trace their roots to the alt.music.nin Usenet newsgroup, while more recent converts have been acquired through IRC, Live Journal and dating/marrying other ninnies), and who now get together periodically to consume prodigious amounts of meat, alcohol and curiously strong brownies, wear Reznor heater shirts and bondage gear, perform cutting-edge karaoke, and comandeer hotel lobbies 24/7 for shooting the bull, freaking out mundanes, making more bad in-jokes than was previously thought humanly possible, and impersonating N'Sync roadies.
Trent? We don't need no stinkin' Trent--we're ninnies for life, with or without him!
Quite possibly the coolest insult ever. Short for nincompoop, it was used often in Victorian Europe and early North America. Insult of choice for monocole-wearing gentry, and anyone with a bit of class.