General Brazilian
calar-se; ficar quieto; cala a boca (informal/rude)
Most common in casual speech
Rio de Janeiro
cala boca; fica quieto
Very direct and colloquial usage
São Paulo
calar a boca; ficar quietinho
Slightly softened version with diminutive
Portugal
cala-te; fica calado; fecha a boca (rude)
Portuguese uses 'cala-te' more commonly than Brazilian Portuguese