> I'm not even convinced they're using proper grammar to say these things. But "good day sir" lacks a verb and subject/object, so it's not even a sentence. On

> I'm not even convinced they're using proper grammar to say these things. But "good day sir" lacks a verb and subject/object, so it's not even a sentence. On the other hand, "what is up" and "how is it hanging" are proper interrogative sentences, as far as grammar is concerned anyway.