Green’s Dictionary of Slang

(US black) excellent.

1997–2000		College Sl. Research Project (Cal. State Poly. Uni., Pomona) 🌐 Phatty (adj.) 1. Good, nice, great, any positive adjective. 2. Big.
2000		Eble Campus Sl. Spring 9: phattie – [...] That was one phattie concert—I love that band.
2000		Ebonics Primer at www.dolemite.com 🌐 phatty Definition: cool Example: That ride iz phatty nigga.
2002		Teen Lingo: The Source for Youth Ministry 🌐 phatty adv. (pronounced ‘fatty’) Incredibly good, cool, top notch. Usually in admiration of a feat or trick.