Taeyeon participates in a new TV Show titled, "Blind Date." It's hosted by Sooyoung and Sunny that is why they got a GG member to be a guest in the first episode. 

3 potential dates are enclosed in special room giving hints about them and what they want to do in a date. 

When these dates finally revealed themselves, Taeyeon was surprised that she chose a co-member, not the two guys. The member was not even Tiffany.