Would you be okay if one of your closest friends dated your sibling? If you think that's a no-no, you're just like Kim Woo Bin and 2PM's Junho, the stars of the new film 'Twenty'.

The two guested on the May 18 broadcast of SBS Power FM 'Cultwo Show'.

Kim Woo Bin was asked, "Would you be able to introduce your younger sister to Junho?"

He thought for a moment before he replied, "No, I can't. We know each other too well, and I don't want to fight with him because of my sister."

Then he was asked, "Are you saying that Junho has some flaws?"

Kim Woo Bin said, "More so than flaws, I think he would imagine naughty things," bringing laughs.

Junho said, "I have an older sister, and I think the same way as Kim Woo Bin. If they fight, I feel like I would get involved."