On March 4, KBS released a teaser for Ong Seong Wu's appearance in one of their shows.
In this teaser, Ong Seong Wu was spotted playing around in a photo studio before an interview.

It was when Ong Seong Wu had placed his jaw on the edge of a piece of paper, then just ripped it off with his hands, pretending like he had cut it with his jaw.

Guesses are that he had tried to turn that into a joke, and it seems like it worked.
A lot of fans left comments under this video, which include, "What a clever joke! It's a really good one!", "You know, Seong Wu never uses scissors. He uses his jaw instead!", "This is the funniest thing I've seen this year! Thank you for making me laugh, Seong Wu!", and more.

(Lee Narin, Credit= 'KBS 한국방송 (MyloveKBS)' YouTube)
(SBS Star)