Colloquialisms are part of all regional cultures. When someone in New York asks if you want to go half on a pie, they don't mean apple. But, in many places, there are words and phrases we use that help define us as denizens (and often natives) of that specific location. Houston most certainly qualifies. Some of them are rather odd words we have adopted while others are phrases too often repeated for all the wrong reasons.
Why we use them is self-evident to anyone who has lived here long enough to adopt our unique language. If you haven't been here long, consider this a primer for how we Houstonians talk and, perhaps, a glossary of sorts for the next time you want to go local.