Relationships between running man mambers

Members	Relation	Details
Kim Jong-kook, Ha-ha, Gary	Kim Jong-kook and Two Kids (김종국과 아이둘)	A twist on the name of the former Korean band Seo Taiji and Boys (서태지와 아이들). Often found in the same team, Ha-ha and Gary are usually under the control of the domineering Kim Jong-kook. Thus, Ha-ha and Gary are always seen shown as being afraid of Kim Jong-kook.
Gary, Song Ji-hyo	Monday Couple (월요커플)	The primary loveline of the show, they show interest in each other on Mondays, which is the day the show was filmed. (Later, the show was filmed on both Mondays and Tuesdays, leading to jokes about the couple not being in effect on Tuesdays.) Since the revelation of Song Ji-hyo's real-life relationship with her management company's CEO, the loveline between the two is deemed to have been removed in episode 82; however Gary sometimes brings this issue back up again, often to comedic effect.
Song Joong-ki, Song Ji-hyo	Song-Song Couple (송송커플) Song-Song Siblings (송송남매)	Another popular loveline, it first attracted attention from episode 15 when Joong-Ki kissed Ji-Hyo on the cheek. They later evolved into a siblings relationship as the Song-Song Siblings.
Lee Kwang-soo, Song Joong-ki	Same-Aged Friends (동갑내기)	Lee Kwang-su claims to be close friends with Song Joong-ki due to their same age (both born in 1985), but Song Joong-ki would often deny their close friendship, leaving Kwang-su appearing depressed. Song Joong-ki finally admitted their relationship in his leaving speech during the filming of his last episode (Episode 41).
Ji Suk-jin, Lee Kwang-soo	New Dumb and Dumber (신형 덤앤더머) Easy Brothers (이지 브라더스)	The New Dumb and Dumber relation was first depicted in episode 65, when they became a duo, acting similarly to the Dumb and Dumber couple of Family Outing.  Later, they were known as the Easy Brothers when they were designated spies for Episode 68, and a clue was offered to the other members that threatened to reveal their identities. The clue was "Easy", a combination of their surnames 이(Lee, pronounced ee) and 지(Ji). Whenever they are paired up, they are also known for performing their "Feel, Touch, Cross!" cheer before each mission. (필, 촉, 크로스!) Initially deemed to be an alliance between the two weakest members of the show, they are quickly becoming a pairing that can no longer be simply ignored.
Yu Jae-suk, Lee Kwang-soo	Yu-Lee (유이) Lee-Yu (이유)	This was formed when Yu Jae-suk and Lee Kwang-su was paired up as a team in Episode 90 by combining both their surnames together, 유(Yu) and 이(Lee, pronounced ee). Throughout Episode 90, Yu Jae-suk and Lee Kwang-soo often does the "Yu-Lee" cross. Often at which, Lee Kwang-su would state that it sounds like the name of After School's UEE. They would say that they miss her. They would finally meet and become one team with her in Episode 137.
Yu Jae-suk, Ji Suk-jin, Lee Kwang-soo	Jail Regulars Trio (감옥 단골 3인방) Lee-Yu-Ji Brothers (이유지 브라더스)	This trio is often eliminated the earliest during Bells Hide and Seek, and meet each other at the jail. They are also known Lee-Yu-Ji, an evolved form of Easy Brothers. It was created as Ji Suk-jin was getting jealous of Lee Kwang-soo being close with Yu Jae-suk, and calling themselves Lee-Yu in episode 81. Asking whether Lee Kwang-soo was with Easy or the new Lee-Yu, Yu Jae-suk replies "that is the reason" ("the reason" is "Lee-Yu-Ji" in hangul), and Ji Suk-jin reluctantly joins them to become Lee-Yu-Ji, which is their last names put together.
Yu Jae-suk, Ji Suk-jin	Suk-Brothers (석브라더스)	The two MCs have been close friends for more than 20 years and that they both have "Suk" in their name. However, Ji Suk-jin is always jealous of the good relationship Jae-suk has with Kim Jong-kook. In episode 27, Ji Suk-jin was referred to as Yu Jae-suk's "sunflower" (always facing towards him) and was officially christened as such in Episode 40.
Kim Jong-kook, Ha-ha	My Big Brother and My Little Brother (우리 형 내 동생)	These two are often on the same team and they have an older brother/little brother relationship throughout the show and often address each other as such in a playful manner.
Yu Jae-suk, Ha-ha	Yu-Ha (유하)	This "loveline" was formed after the announcement that Song Ji-hyo was dating the CEO of her company in episode 82. Ji Suk-jin commented that a new loveline was needed in the show. Following which, Ha-ha commented that he was preparing for a love line and Yu Jae-suk immediately jokingly replied, saying that he couldn't sleep because he has been thinking about Ha-ha too much. They often argue with each other with the superpowers given on episode 74. "The one who controls time" and "The one who drives me crazy" are the top two said by Yu Jae-suk and Ha-ha.
Kim Jong-kook, Lee Kwang-soo	Kook-Su (국수) Tiger and Giraffe (호랑이와 기린)	This was formed in Episode 82 when Lee Kwang-su and Kim Jong-kook were paired into a team. So their names were combined to form "Kooksu" which is a pun because it also means "Noodles" in Korean. Also, since Kim Jong-kook resembles a tiger and Lee Kwang-su resembles a giraffe, their relationship is also known as Tiger and Giraffe. This happened again in Episode 84 where Lee Kwang-su and Kim Jong-kook were chosen by the opposing team to pair up together with paper handcuffs, leaving both of them stuck to each other for the rest of the episode.
Ji Suk-jin, Lee Kwang-soo, Kim Jong-kook	Kookisy (국이지) Serengeti (세렝게티)	Pronounced as "kook-ee-ji", it was formed by combining all three of their names together by using the first syllable, 국 (Kook), 이 (Lee, pronounced ee) and 지(Ji). In Episode 86 after some loose references in previous episodes, Kim Jong-Kook overthrows the "Kookisy" by pointing out the tiger and giraffe pairing with Lee Kwang-su and then saying that Ji Suk-jin is like an "impala" which makes them the "serengeti" team.
Ji Suk-jin, Lee Kwang-soo, Song Ji-hyo	Mong-easy (멍이지)	Pronounced as "mong-ee-ji", it was formed by combining "Mong" as in Mong Ji-hyo, "Lee" as in Kwang-soo's surname and "Ji" as in Suk-jin's surname. They are often teamed together in many episodes and the nickname was formed especially after episode 96.
Ha-ha, Lee Kwang-soo	Betrayal Masters (배신 마스터)	Ha-ha and Lee Kwang-soo are well known to betray in races. This nickname was formed when both of them were spies in episode 99. In episode 106, Kim Jong-kook said that he eliminate both of them first as they were constantly betraying. In episode 109 and 110, this duo made a return again.
Ha-ha, Ji Suk-jin, Lee Kwang-soo	Traitors Club (배신자 클럽) Betrayal Team (배신 팀)	After Ha-ha and Lee Kwang Soo became betrayal masters, Ji Suk-Jin was added and they became the Betrayal Team. In Episode 146, there was an episode featuring them, where they were listed as the Traitors Club who attempts to steal a treasure.