MBLAQ's Lee Joon drew attention for his ability to use profanity, despite being an idol star.

On the May 1st broadcast of SBS 'Strong Heart',�Super Junior's Eunhyuk questioned Lee Joon about his relationship with actress Jung Ryeo Won.

"I know that Ryeo Won had asked Donghae for Lee Joon's number," he said. "I want to know what happened afterwards."

"Ryeo Won noona personally called me to cast me for a cameo role playing her boyfriend in 'Salary Man'," Lee Joon said.

"There was a scene where she needed to use profanity really well, but she doesn't really use such words and couldn't seem to pull it off," he continued. "We filmed that profanity scene for about 5 hours."

"But I encouraged her, telling her that she is someone who can be proficient at using profanity," he added. "And I helped her, telling her all the swear words."

Then, MC Shin Dong Yup not missing a beat, asked Lee Joon to curse on the spot. Lee Joon hesitated for a moment, but then swore to his heart's content on the program.

"I'm going to look like I have no class," he said concerned. The other guests then labeled him the idol who curses the best, causing the entire set to laugh.

Source & Image: OSEN via Nate