Fajitas and Margaritas, don't get no better than that. We use to cross the Border every year, this place has the best food North of the Rio Grande.
One of my favorite Tex Mex places in Frisco, Texas, is called La Hacienda Ranch. The "Texas Frozen" margarita is awesome--but one should never, ever drink three. I did that last spring and felt hungover for five days.
I use to eat with friends at a place near SMU campus, I think it was called the Blue Goose Cantina? I don't know, most of my life has been a blur.