Word is Director Lee Joon-ik didn't actually have the ending scene planned out at first.

He was vaguely thinking, 'Maybe just end it with a close-up of Park Joong-hoon's smiling face??'

But actor Ahn Sung-ki felt it made no sense for only one person to be in the final shot since they were co-leads, so he pitched an idea.

He suggested walking in while playing the umbrella like a guitar and singing to break the awkwardness...

Then he'd walk up and hold the umbrella over Park Joong-hoon, who’s acting all grumpy and sulky. Once that idea was out there...

Apparently, the entire staff started clapping and were totally blown away.