Super Junior's Heechul revealed Taeyeon's rougher side on the August 12 episode of 'A Hyung I Know / Knowing Brothers'.

Heechul revealed, "Taeyeon is a homebody like Min Kyung Hoon. She watches 'A Hyung I Know' and messages me saying, 'Oppa, you seem like a crazy person.'" The 'A Hyung I Know' cast then agreed, "It's true that you're crazy. Taeyeon said it right."

The Super Junior member continued, "I met Taeyeon near the bathroom a bit ago. I asked her how much I can say about her, and she cursed at me." Taeyeon responded, "If you're going to insult me, you should at least make it funny!"