On the September 3 installment of 'Running Man', Soyu appeared as a guest and asked Lee Kwang Soo this particular question.

During the show, Soyu was giving out pilates massages to the members of 'Running Man'. As each member was trying it out, Soyu mentioned the next body part to be massaged will be the butt in which Lee Kwang Soo volunteered right away. 

However, as soon as he raised his hand, the rest of the members teased him and tried to stop him by saying, "No you can't, you don't have a butt" which made Soyu ask in a surprise, "Oppa, you don't have a butt?!" 

To this Lee Kwang Soo said, "No no it's just a misunderstanding...okay, at one point in my life I didn't but that's not the case anymore!" Yoo Jae Suk then joked, "I pinched his butt a little while ago and it took me forever to find it" which made everyone laugh.

Were you able to catch 'Running Man' this week?

SEE ALSO: Lee Kwang Soo fails to hold back his agonizing expression while receiving a pilates massage from Soyu