Byul, who's known for her cute appearance, brought out her sexy side on November 3rd's 'Immortal Song 2'.

The singer performed her own rendition of Lim Joo Ri's old-school hit ballad "Put on Thick Lipstick". Before she lost her chance at winning first, she sent a message to her husband, HaHa.

Byul stated, "Oppa, instead of a rerun of 'Infinity Challenge', I hope you watch this instead."

Check out her performance staring around the 9:40 mark below!