Rain and MAMAMOO teased their collaboration on 'Hangout with Yoo'.

On the July 25th episode of 'Hangout with Yoo', MAMAMOO made a surprise entrance in the studio as Rain was working on his solo track for the SSAK3 dance group project also featuring Yoo Jae Suk and Lee Hyori. On his upcoming song "So Fun", Rain expressed to MAMAMOO, "Firstly, thank you so much. I strongly requested you. I thought that it would be best to do this song with MAMAMOO."

Before heading into the studio, Rain said, "I divided the parts up. Please look at them if it's okay." MAMAMOO were more than happy to accept the song as is, and the members commented, "It's good," and "We trust you, BiRyong."

In other news, SSAK3 dropped the MV for their official debut song "Beach Again".

Are you excited for Rain and MAMAMOO's collaboration?