back then when they weren't debuting yet, they had this live stream called 17TV and there was that one episode where Jihoon (the midget) cornered Mingyu (the giant) and he held up a guitar in the air and jokingly threatened that he would hit Mingyu with the guitar lmfao. pretty sure all the fans found it funny which is why it's always being used.

Oh haha he does it as a joke really. It's sort of like Luhan with his shin-kicking. But Jihoon can be quite violent at times too,but by hand and not by using items.