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1.
1. A casual way of saying "No thanks"
2. A playful way of saying "hell no!"
1. "Would you like some soup?" "Nah, I'm good thanks."
2. "Yeah it hurts like hell. Want a demonstration?" "Nah, I'm good, lol"
by Raych November 19, 2004
 
2.
This is a phrase used to express that ur not gonna do something you dont wanna do. This happens to be the best comeback to anyone asking you to do something for them; It lets the person know that doin a favor for them is not "good" for you.
Ruby Tuesday Cook: "Hey man can you prep me some Tomato Mozzarella"?

Worker who is NOT the Prep Person: "Nah im good".
by zarreff May 01, 2011
 
3.
A more polite way of saying "I don't give a flying fuck" in Instant messaging. Although McDonald's new bullshit slogan uses the same lack of punctuation,nah im good is not used by closet homosexuals like Justin Timberlake.
0TTR: It's PEANUT BUTTER JELLY TIME! *link to eBaum's world*
mrterryakiman: nah im good
by 0niTTRay January 05, 2004