Girls' Generation's Sooyoung revealed why she's known as TVXQ Yunho's 'natural enemy.'

During filming for the upcoming episode of 'Knowing Brothers', Sooyoung featured as a guest alongside her 'Tell Me What You Saw' co-star Jin Seo Yeon. The Girls' Generation member revealed to the 'Knowing Brothers', "My nickname is TVXQ Yunho sunbaenim's 'natural enemy.'" 

She then explained it all started when a video of her rehearsing Girls' Generation's "Party" became viral. Unlike Yunho, who's known for being "passionate" at all times, Sooyoung can be seen going through the motions with little effort as it's only rehearsals.

Sooyoung said, "I thank the netizens who had fun watching the video," adding that she felt slight embarrassment over it.

Check out the video below!