Ah yes, waxing philosophical. The most definitely-not-suspicious reaction a Jonouchi could have.

Maybe he still can't tell what Jonouchi's hiding, but he can tell the guy is hiding something, and his own flat stare back will hopefully tell Jonouchi that he knows, too...

"Why can you hear Kul Elna." Completely deadpan. "Those are mine." ...And now the deadpan's taking on a very 'what are you doing in my locker' vibe.