Recently, 'The One' revealed that he scolded Super Junior's Leeteuk and Shindong the most while conducting vocal training for singers. tvN's "Taxi"aired a special episode called 'The Singer Who Teaches Singers'. The One had taught an extensive list of singers, including TVXQ, Super Junior, and SNSD's Taeyeon. But out of all his trainees, he revealed that he had scolded Leeteuk and Shindong the most. The One explained, "Leeteuk had the habit of going to the bathroom whenever he had to practice. Shindong likes to joke around a lot, so he often fooled around and sang sad songs in a funny way. The two are really funny so I suggested that they sing a duet together". He also revealed his special relationship with Taeyeon and said, "I met Taeyeon when she was a second year student in middle school. I gave her a lesson once every week. Her concentration was remarkable and she had the look in her eyes which you normally couldn't find from people her age. When I heard that she debuted as a SNSD member, I was really surprised". The special episode is set to air on March 17th. Source: Newsen via Nate