Peggy will slide you the keys to the Staff Room. You do not actually have to go grab the Pizza Box, you can just continue with the call without it.
Go downstairs, through the door behind the reception, take a right and enter the Staff Room. Grab the Pizza Box inside a garbage bin by the left-most wall of the room.
Go dial Peggy and say you're ready to go.
In order to save Virginia, choose the following prompts:
1. "Call Ponty's Pizza."
2. "Hey, dude."
3. "Garlic bread!"