The Hamlet Project

Polonius says Pooh! Does anyone else in all of Shakespeare use the word “Pooh?”
No. It is his and his alone.
What would he say it means?
Is it like Pshaw? Or “bullshit!” or “Phew?”
Polonius says Pooh, though.
Pooh pooh pooh
Maybe he’s poo-poo-ing.
Does poo-poo-ing something come from Polonius?
Pooh!