Because apparently Ahn Jaewook can.
Appearing as a guest on “Delicious Invitation” on July 2nd, the question of “Do you have an SNSD member you can contact immediately?” came up. He picked up the phone and called Sooyoung, who answered. MC Shin DongYeop questioned whether it was really Sooyoung or not, which was proved when Sooyoung sang.
Sooyoung commented that Ahn Jaewook used to perform with her older sister.
Source: TV report, Arts News, Soshified
Posted By: dreadtech@snsdkorean