On February 26th, Apink's Oh Hayoung made an appearance as a special MC on the 196th episode of the KBS 2TV variety show "Boss in the Mirror" (also known as "Donkey's Ears").
During the show, when asked if she was close to Kim Heechul, Oh Hayoung drew a line by saying, "We're only close for the sake of the broadcast".
Then she said that she had something to reveal about Kim Heechul, "Since our debut, we used to visit him to greet him. He would ask us questions like 'Who looked the coolest in stage outfit?' and 'Who stood out the most on stage today?'".
Kim Heechul was taken aback and asked, "Didn't you come here to promote your album?" to which Oh Hayoung replied, "Our album hasn't been released yet."
When Kim Heechul further questioned why she came, Oh Hayoung responded with "I'm a TV personality, should I not appear on TV?".
This caused Kim Heechul to declare that he would suspend filming, saying, "I will stop filming here," and bringing laughter to the set.
Source[1]