Note: 企画 is used to describe a project / program planned for a stream, so 表 = what they claim they are doing, which is a reverse totsu in this case, and the hidden "camera" project is an 裏企画 which they have to do without being exposed.
For the challenge worth 5 points, it's an incoherent sentence that sounds kinda similar to "thank you very much" in Japanese.
"Zukkun" is a running joke from here: https://youtu.be/pv-ixv-FYa4
Original stream: https://www.youtube.com/watch?v=dlmkPXsYro8
Please subscribe to the livers mentioned in the video!
Usami Rito 宇佐美リト: https://www.youtube.com/@UsamiRito
Kuzuha 葛葉: https://www.youtube.com/channel/UCSFCh5NL4qXrAy9u-u2lX3g
*I am not a native Japanese and am doing this purely as a hobby.
Please feel free to point out any areas for improvement!