On the September 17 broadcast of 'Weekly Idol', idol groups NU'EST and FIESTAR made a guest appearance and did a freestyle face-off, showing off their sexy and silly moves to the amusement of hosts Jung Hyung Don�and Defconn.

SEE ALSO: Kim Byung Man says he feels betrayed after hearing the news about the 'Law of the Jungle' spin-off show 'Jungle Bob'

Starting at the 20:30 mark in the video above, FIESTAR's Yezi starts us off with a popping dance to Kanye West's "Stronger", only to be unexpectedly joined by Ren who attempts to follow. Other highlights include JR's flailing dance and his spastic version of AOA's "Miniskirt", Yezi's booty popping session, and Ren's surprisingly accurate cover of Girl's Day's "Something".�

In the same episode, the two idol groups danced to their own choreography and shared funny impressions.�

Check out the hilarious clip above and stay tuned next week, when 'Weekly Idol' returns with T-ara as its next guest!�