What does Thomas say in the S4 finale when Katie asks "what's going on in there?" referring to Naomi dancing in the living room?

Katie asks Thomas "what's going on in there?" then he mumbles something to which Katie Antworten "huh?" and then Thomas just says it's time for our french lesson... I think it might be in a different language (I'm assuming French) oder I just can't hear it but it's been really pissing me off lol