Game sees game. As a professional liar about his physical and mental state, Kaiba knows what Yuugi's doing, and really doesn't give too much of a fuck to interfere about it at this point. Instead, he follows Yuugi's movements, which take him to...something colorful and obtrusive on one of their sparse furniture pieces.

Then, and only then does he at least shuffle to the edge of his bed, still seated, and cross his arms while scowling. If Yuugi looks his way, he'll mouth:

What is it?

Because by all accounts, it looks like a goddamned cupcake, and aside from being insulting...it reminds Kaiba that he can't remember the last time he's had anything to eat.