What caused Sunny to laugh out loud on the 'David Letterman' Show?

Last night, Girls' Generation made their American television debut on the 'The Late Show with David Letterman'.

Before their performance, David Letterman remarked, "Our next guests are a very popular group from South Korea who have� just released their first album in America, it's entitled 'The Boys'. Please welcome, making their network television debut, Girls' Generation!"

During his introduction, viewers chuckled as member Sunny could be seen on the left side of the frame, in her ready position. Sunny who also saw this on the monitor could not help but burst out in laughter. After Letterman's introduction, the girls put on a fierce live performance of a newly edited English version of "The Boys".

Netizens who saw their performance responded positively with comments such as, "Cute. She must've thought it was funny too", "They rock the show where ever they go", and more.

The girls also performed on ABC's 'Live With Kelly' earlier today and will also be holding an interview with 'Extra TV'.



This may be the girls' most fierce performance yet. What did you guys think?

Source & Image: IlganSports via Nate