How would Tatara react if Eto surprises him by speaking Chinese to him?

Tatara: Wait.

Eto: Yes?

Tatara: You’ve known Chinese all along, haven’t you?

Eto: *smiles*

Tatara: So you’ve understood all of my conversations on the phone…

Eto: I particularly liked how you referred to Ayato as Blueberry Edgemuffin. 

Ayato: WHAT

Eto: *runs off, laughing*

Tatara: *now has to deal with angry Blueberry Edgemuffin*