Riddle/Joke

J asked me this riddle the other day...

"You are in a room with four walls, a ceiling and a door that is locked,
how do you get out?"

I didn't know so I guess with "you use a key?"

"No Mom! You only have a PIANO!"

I laughed so much at the mistelling that I had to ask for the answer another day.

"You try all the keys"