Green’s Dictionary of Slang

1. (US) mediocre, second-rate.

1994		M.C. Hammer ‘Pumps and a Bump’ 🎵 cited in Vibe (Boulder, CO) Mar. 2004 144/2: ‘You wiggity wiggity wack if you ain’t got biggity back (Awwww!)... / I put my fingerprints all over that rump.’.
2006		L. Dalecki Kid B 123: Any wiggedy-whack punk can flip from his belly to his back. But making it flow, with your legs to keep the rotations going smooth, is what it’s all about.

2. (US) exciting.

2009		F. Tinsman Chaos and Rage 128: Ernie bet it would seem like a slow news day in Brazil for months, after tonight’s super wiggedy-whack festivities.
2009		J. Richmond Legoland 32: For two E-Z payments of five dollars you get high as a kite, sharp as a tack, get wiggedy wiggedy wack, or your money back.
2013		M. Becket Surredner to Sultry 86: Rachel performed a few hip thrusts and a stiff version of the Running Man while Leah broke into a fit of giggles. ‘Tell me that’s not fresh-dope-ill.’ ‘Wiggity-wack,’ Leah said. ‘You’ve still got it fly girl’.

3. (US) unstable, bizarre.

2002		C. Miles Wedding Captives 117: ‘Travis, have you gone completely wiggedy-whack?’ Thea cried.
2013		Cooper & Bellmont Totally Sweet 90s [ebook] The kids from Kris Kross are now in their thirties. Can that even be possible? It doesn’t get more wiggedy-wiggedy-wiggedy wack than that.