'THE TaeTiSeo' aired as usual on September 30, showing the brightly smiling members of TaeTiSeo as they danced with SISTAR's Bora, roamed in New York City, and more.

After the trio rehearsed on Mnet's 'M! Countdown,' they headed backstage where Tiffany and Seohyun cutely and mysteriously told the camera that they were introducing a fourth member of TaeTiSeo!  Cue drum rolls, please.  Cutely, the two girls parted to reveal SISTAR's Bora!  The three of them then danced to SISTAR's "Touch My Body," doing the "apple hip dance."

In addition, TaeTiSeo had a fun time in New York for Fashion Week.  They enjoyed some of the delicious food in the city, souvenir shopping, and sight seeing as they visited the Statue of Liberty.  Seohyun even headed over to watch the musical, 'Chicago,' showing her love for musicals.  She said, "I really want to be in a musical.  Later on, I want to do 'Chicago' in Korea." 

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In their hotel room, Taeyeon said, "Whenever we go abroad, I always have my own room, but it's very lonely," and showed off her perfect bare face.  She could not fall asleep, so she said, "When I can't fall asleep, I listen to music or play games on my phone or watch TV.  I think I'm going to play a couple games then sleep."

Check out clips below and make sure you see the whole sweet episode!