While eating with Gongchan, Sandeul was asked why he didn't sing the way he usually does when he appeared on 'Mask King'. He answered, "When I sang like that, people already enjoyed it so much. I was worried that if I were to have sung it the way I usually do, that people wouldn't like it."

SEE ALSO: CNBLUE members have hilarious reactions when a former troublesome member appears unexpectedly during a live stream

The idol singer then proceeded to sing the difference between the way he sung on the show and the way he usually sings, while explaining, "The song 'Emergency Room' is sung by a lot of guys at karaoke because they want to look cool. I was practicing while thinking about how I used to sing it at the karaoke." 

Gongchan then sneaked in a question and asked, "You said that you sing like that to look cool, then there must have been a girl around to look cool in front of. That's why you sang like that," causing Sandeul to squirm while trying to make an excuse.

Check out a clip from this week's episode of '4 Things Show' above!