Surprise Sanae sliding into Nibutani at the beginning cracked me up.
Their interactions stealing the show in general. Their instinctive fighting upon entering proximity to one another was particularly amusing. And they found something to agree on: laughing their asses off at Isshiki's glowing shaved head.
Isshiki jumping over Nibutani rolling around was a nice visual gag.
And oh god, Kumin. Her end scene was stupidly adorable.
It was nice to see the class girl rank thing come back and bite the guys in the ass for a change, though I felt they got off too easy. Wish Nibutani would have pushed the issue and not let Isshiki enable the others to get away with it. Yuuta never shows any concern except for his and Isshiki's well-beings and the whole thing still comes away with a whiff of "It's a Bro thing; the girls don't like it so just don't get caught."
I did enjoy the girls' reactions, both verbal and body language. And at least there was some public humiliation. Just wish it would have gone a bit farther. Oh well.
Anyway, great episode as usual.
Avatar: Kuroneko (Ore no Imouto ga Konnani Kawaii Wake ga Nai)