I watched a Brazilian comedy movie "Até Que A Sorte Nos Separe II", in which the wife calls her husband "muxoxo", but it would be a word the couple made to treat each other affectionately. I only heard that word in this movie.

Thank you, Andreisa! I think I've got it now.

Wow... It is a difficult one, because it is ( or was, nobody uses it) a regional language expression to describe a click that someone does with the mouth to indicate dissatisfaction. I do not know an english expression that summarizes the action. It could be written, in the past, in a sentence like this: He did a click sound with his mouth to demonstrate his dissatisfacion. Fazer um muxoxo: To make a sound with the mouth ( tongue and lips) to demonstrate dissatisfaction.

Primeiro o que é "muxoxo"? rsrs