"Oh, come on. This is an easy one. You can't truly be this stupid. Do you need me to repeat it?"

The Riddler speaks through a speaker hidden in the wall, his face on a giant TV screen in the room you're trapped in.

"What do you throw out when you want use it?"

He repeats the riddle, interlocking his fingers and resting his chin on his hands, waiting for you to answer him.

"Come on. You can do it. Just think. Think. Think."