@Rye In episode 4, Ojou touches Gyaru-ko and Ota-ko in a way that makes them moan. I won't give you context because I'm a terrible person.
On a more serious note, I personally like the dynamic of it. Ota-ko asks a question (generally about sexual things or about boobs), Gyaru-ko answers and gets embarrassed when she realizes the nature of the question, and sometimes Ojou tries to answer without really understanding the conversation they're having.