César is so confused when she starts laughing at him, because he doesn't understand why it was funny. So he reviews what he said before it clicks. Then starts cracking up with himself. Even if he's a bit concerned she might feel his, well, groin, (oh her being closer is not helping that) it's still hilarious. He loops on arm around her upper back (to steady her, mostly) while bracing himself with his other hand on the desk, because otherwise he might fall over and take her with him.

"No—" César fails to explain. "no, I meant—" Another peal of laughter. "It's Spanish."