Twice, the South Korean sensational girl group, have uploaded a music video teaser for "Knock Knock". Reportedly the trailer sends an invitation to join the party, and it looks like the girls are having a sleepover in their cute pajamas. Netizens who have watched the teaser commented that they are really excited, and are eagerly waiting for the release of the group's special album.

Only last month, according to the post of WikiPedia, the music video of the group titled "TT" hit around 100 million views, apparently becoming the fastest K-pop group music video to do so. It apparently also broke Twice's own record previously set by "Cheer Up". Further, also last January JYP Entertainment, the agency handling the South Korean girl group, announced Twice's first solo concert within just a year and four months after their debut in October 2015. The three-day concert titled "Twice 1st Tour: Twiceland, The Opening" will be held this February at the SK Olympic Handball Gymnasium. This is reportedly the first stop of the group's world tour.

Accordingly, JYP Entertainment also announced on January 18, 2017, that Twice will release a special album after the Korean leg of the concert tour. The album, titled "Twicecoaster: Lane 2", will contain the title track "Knock Knock", and is set to be out late February.

According to Allkpop, Japanese auto maker Audi also jokingly mentioned Twice in their tweet. The Japanese Twitter page for the car brand apparently said that they are "TT' too and wanted to suggest they are the original because apparently, this is already Audi TT's 19^th year. The alleged photo posted along with the tweet showed the car model with Twice's signature "TT" move. It is further said that it is cute for the Audi tweet to mention the K-pop girls, especially that three of the girls are Japanese. Maybe in the future, Twice can be seen modeling for the car.