The United States is a vast and diverse nation with a huge assortment of languages and dialects. It's perhaps no surprise, then, that in a country with at least 350 languages, you find a great deal of variation in the slang terms—some of which are downright strange.
These bizarre phrases come in all types, some of the most common of which are place descriptions—highways, intersections, concert halls, mountain ranges, etc. In Colorado, for example, they use the term "Mouse Trap" to describe the junction of Interstate 70 and 25 in Denver. Everyone knows what this is even though it might baffle outsiders. Similarly, in Kansas, the word "kaw" is synonymous with the Kansas River. In Atlanta, they use "OTP" or "ITP" to describe one's proximity to Interstate 285 ("OTP" is "outside the perimeter" while "ITP" means "inside the perimeter.") Out-of-towners have no idea what the natives are talking about.