clip is unsubbed, but below is soompi's description of what happens in the clip
In the preview, AOA is warmly greeted by the cast members as they walk into the classroom, and Kang Ho Dong introduces them as “Ace of Angels.” Seolhyun tells the cast, “Seeing you for the first time in a while, you guys look really cool.” However, she immediately adds, “I’m lying.”
Yuna tells Seolhyun to stop, and Jimin makes everyone laugh by joking, “She thinks she’s the center of the universe.” Jimin continues, “Hyejeong laughs in an ugly way,” and Super Junior’s Kim Heechul accuses Hyejeong of picking her nose during her last appearance on the show.
Chanmi then complains about her fellow members, sharing, “I want them to have more passion. They keep simplifying the choreography.” Demonstrating a part of one of their dance routines, she explains, “[For example,] we have to do five different moves like this, but the members just want to do [three moves] like this.” When Kang Ho Dong asks Chanmi if she’s suggesting that other members are dancing halfheartedly, the other members chime in with rebuttals.
Seolhyun later suggests a game that tests out the cast’s thigh strength, and the preview ends with the girl group and cast members facing off in a fierce game of gonggi (Korean jacks).
source: JTBC Entertainment, soompi