Popular South Korean variety show 'Happy Together' has been celebrating airing of 500 of its episodes with a number of special episodes populated by special guests. Two such special guests happened to be actor Jo In-sung and singer-actress IU.

The program director of the show talked about their special appearances on the show. As noted by website Soompi, on the May 25 broadcast of 'Happy Together,' the cast members tried their best to invite three famous South Korean stars to come congratulate the show and its members on its achievement of airing 500 episodes. The three stars were Jo In-sung, Song Joong-ki and Gong Yoo.

It was Ji Suk-jin, who secured the number from Lee Kwang-soo and requested Jo In-sung to appear on 'Happy Together.' The actor actually complied; a gesture which moved the PD of the show. Jo In-sung is also good friends with MC of the show Yoo Jae-suk.

"We thought it would be great if we could even just get [Jo In Sung] on the phone to congratulate the show. We had no idea that he would actually show up. I was very touched by his guest appearance on the show," the PD said adding, "Jo In Sung was the star of the May 25 episode. He was very crafty and fun on the show."

Another special guest to appear on the episode was singer-songwriter and actress Lee Ji-eun, better known by her stage name IU. IU is also good friends with another MC of the show Park Myung Soo. As noted by Soompi, Park Myung-soo called IU lying he was sick. He also told her he hadn't eaten all day and asked her to buy him spicy rice cakes.

Despite suspecting something was wrong, IU relented and brought the spicy rice cakes as asked. "IU came in a taxi by herself. She went to Gangnam by herself to purchase the spicy rice cakes and this was when 'Palette' was topping all the major music charts. We were moved by how she quietly fulfilled his request on her own," the PD said, commending her sense of loyalty towards her good friend, thinking he was unwell.