Singer IU talked about the first impression she had of MBLAQ's Thunder during a phone call in "Idol Manager."

"Idol Manager" airing on Friday, MBLAQ members invited their best friends and talked about their past.

On this day, Thunder's friend Kim Sung Gu that spent his training days together with IU talked about the different sides of Thunder that has not been revealed before.

A surprise phone call of IU was also shown. When Park Kyung Lim asked about Thunder, IU said, "I was really shocked at first. I thought to myself, 'Can a human being look like this?' It was to the point I could not look at his face."

IU also talked about embarrassing episodes of Thunder, bringing laughter to the set.

This episode will be aired on Friday through MBC's "Idol Manager."