One variation of the word can be for burping, as said above. When one takes a bite of food or a drink of soda, buh can be said with a burp aiding it, or by itself.
This can also be used for many things. If someone begins to talk about something which is of no interest to you, simply say Buh and it wall all go away.
guy 2: Buh........
guy 1: *Takes bite of sandwich* Buuuuuhh...... *blows out side of mouth*
guy 2: That smells! You are such a cutie patutie. I fight ya!
2) a simple grunting noise made to substitute the use of any word that makes sense.
2) a: "want some tea?"
a: "well...? is that a yes or no?"
a: "what the hell does "buh" mean?"