This is a nifty little phrase I picked up. Let me give you a few examples and see if you can figure out what it means:
Habla quedito porque va a empezar la matiné
Habla quedito nos van a escuchar
Pon la musica, pero quedito
You've probably picked up the meaning of our phrase, habla quedito, but let's translate our sentences anyway.
Talk quietly because the show is going to start.
Talk quietly or they're going to hear us.
Put on the music, but not too loud
That's it! Pan comido, right? Don't you wish everything in Spanish was this easy?