Choi Kang Hee and Lee Moon Sae are slated for an appearance on '1 Night 2 Days' upcoming 'best friend' special.

According to a broadcast insider, the fixed cast members�were whisked off on a trip with their 'best friends'. For this special trip, Joo Won called in his '7th Grade Civil Servant' co-star Choi Kang Hee, and Sung Si Kyung invited his respected sunbae Lee Moon Sae.

The concept and location of the vacation haven't been unveiled to the public yet, but the two stars are said to have surprised everyone with their cool personalities and hidden charms.

This 'best friends' special will air mid-May!