TEEN TOP transformed into sexy, bad boys on January 5th's 'Immortal Song 2'.

The idol group did a tango rendition of Um Jung Hwa's well-known�hit "I Don't Know". The members performed alongside a tango dancer in a red dress, showing their bad boy side and impressing the audience.

The other singers on the show commented that the members of the teen idol group have become surprisingly masculine.

However, UV took home the ultimate win.

Check out TEEN TOP's performance below!