Now that you’ve mentioned the mattrass, your best friend Giovanni puts a paper bag over his head. How do we get him to remove it? Just talking doesn’t help.
Open the cabinet and take the BOX out. On the bookshelf is a red book. Take it, actually, take just one PAPER from it. In your inventory, look at the paper.
Use the box on yourself to stand in and talk to Giovanni. Cite the paper and you’ll win.
Game source: A copy of the game was found here on the internet.