Not sure if it's been mentioned here or not, but the Mexican food truck, Taco Loco, at 15th and Boulevard (SW corner gas station) is legit. We've been there a few times now (most recently last night) and the street tacos are very, very good. As good as any you'll get in S. OKC. Plus, they are still just $1 and $1.50 - 3 tacos with rice and beans $5. Been quesadilla ($5) is excellent too.

Every time I've been there has been 4-5 other people getting food too.