Long story short, Jaesuk wanted to prank Kwangsoo, but couldn't figure out what prank should he pull. Without much thinking, he decided to purchase some random drink which was promoted by a celebrity friend of his, which could switch your gender. Jaesuk didn't believe in such magic as he remembered reading those kinda stuffs in fairytale books when he was a toddler.  However, Jaesuk being his silly self decided to buy it and give it to Kwangsoo. He said, "Yah, Kwangsoo, i