Crossword puzzle clue "impossibility if you keep your mouth shut"

Impossibility if you keep your mouth shut

Yell at your parents for not making the soup salty enough because your crush told you your mouth looks too funny to kiss, e.g.

Superhero who can't keep her mouth shut?

"Shut your mouth!"

"Shut your mouth!"

Say "I don't know" with your mouth shut

Work + play + keeping your mouth shut, according to Einstein

"___ better to keep your mouth closed ..."