When you stick your tongue outside of your mouth and gently blow, it makes a common sound to indicate "whatever!" or "I don't like your answer/response" or "Yes, you are smarter than I am."
What is the name of this sound and how do you spell the sound?
Best Answer
I wonder what the linguists will make of this question.
It sounds as though you are describing what is colloquially known as 'Blowing a Rasberry'.
As to how you would represent it in writing, I'm a bit flummoxed. Experiment with the following (all as long or short as you wish);
Brthrthrthrthrth
Pthwrzrthwrzzz.....
Much better than the internet Pbbt. You could have started something here.