A.K.A. "it's ok." This term is used by a more ghetto audience.
Cindy: OMG that boy jacked your car!
Billy: It's straight
A phrase synonymous with "it's all good" or "don't worry about it." This idiom starkly contrasts with its polar opposite phrase, "that's gay." I'm not sure when sexuality became a parallel point of reference for agreeability.
Guy 1: Hey man, I know I owe you 20 bills, but is it cool if I pay you back next week?
Guy 2: It's straight.