did anyone know about yoona and fany skirt incident, is sooyoung involved?

This is what I mean by Yoona being the rudest. I don't like her. And this is why. She's so rude! How come she didn't just plain ask Fany first!? She's crazy. That was so rude of her. And Fany was her unnie too... Tiffany was so embarrassed. Yoona is just a pretty face and nothing more. She has no talent either! If someone ripped off her face she would never be in SNSD.

A fancam taken before SNSD peformed ‘Etude’ on Music Core captured Yoona lifting Tiffany’s skirt and looking so shocked at what she saw underneath. Yoona then can be seen mouthing ‘You didn’t wear it?’. She was of course referring to their ‘shorts’ that they have to wear underneath their skirts to avoid flashing the audience during their performance. Yoona obviously worried, Sooyoung who’s standing next to her grabbed Tiffany and turned her over to check if anything’s visible.

It's just a misunderstanding. On August 17th, SNSD's member Yoona, Sunny, Sooyoung and Yuri attended the YSMM Talk show.
In there, YoonA talked about the video that showed her lifting up Tiffany's skirt before Etude performance. She wanted to clarify this misunderstanding. "Tiffany forgot to clip her skirt with the cloth together and I just wanted to see if it can be seen or not, because when we dance, it could show."
She continues toe explain the situation, "And I asked her 'You didn't clip it?' but in the video, it looks like I said 'You didn't put it on?' That's where the misunderstanding starts."

Oh I don't really can explain.Sooyoung has a little part you know