Since may thread na, might as well put in some useful content.
For relatively new viewers, some may find the members personalities "strange" or "OA", but keep in mind in Korean variety shows, members make their own "characters" to make things more fun.
Key characters include:
Yoo Jae-suk = Yoomes Bond (James Bond parody), Grasshopper, Yoo Hyuk (dancer persona)
Gary = Peaceful Gary, Monday Boyfriend, Sudden Commander, Random Mr. Capable
Haha = Haroro (parody of Pororo, a children's show), Kid (which is why he might seem childish at times)
Kim Jong-kook = Sparta, Commander, Tiger, Kookie (cute nickname), Mr. Capable
Song Ji-hyo = Ace, Bad Ji-hyo (you'll find her acting feisty and smacking people at times haha), Monday Girlfriend, Lucky Goddess, Mongji (Blank-ji, you'll find her zoning out and sleeping a lot)
Lee Kwang-soo = Icon of Betrayal, Giraffe, Prince of Asia
Ji Suk-kin = Big Nose Brother, Race Starter (once he gets eliminated, the real race begins because he usually gets ousted first haha), Impala