We also sometimes request a "doggy bag", which is the same thing as take-out.
Example: "Can I get a doggy bag to go?"
EDIT: Here's an example from Here's more proof.Can I Have This to Go?
During a recent meal at Craftsteak, I was impressed by the way the restaurant handled a request by one of my companions that unconsumed portions of food on the table be wrapped up so she could take them away.
After servers cleared the table, one of them returned with a claim check instead of a doggie bag.