Fans of SBS's "Inkigayo" were treated to a fantastic stage featuring Jewelry and ZE:A for the show's February 13th Valentine's Day special. To recap, Jewelry performed "Back It Up" with their labelmates ZE:A, and brought down the house with their fun energy. ZE:A's Kwanghee (a.k.a, the second "King of Kkab"), Siwan, Minwoo, and Hyungshik appeared in the midst of the performance and engaged in couple swing dances with Jewelry. They also mastered Jewelry's "Jewel Swing" dance, capturing the viewers' attention. Recently, the girls of Jewelry revealed backstage pictures they took with the ZE:A members through Twitter.. Netizens commented, "I loved the collaboration stage. It was more fun! Keep performing together", "Jewelry looked confused at Kwanghee's kkap dance. I thought his dance was quite entertaining!", and "The performance looked perfect. The matching pink outfits looked good on everyone!". Check out the performance below! Source: Sports Chosun via Nate