Anna Kendrick is speechless about the success of 'Cups'

"Pitch Perfect" star Anna Kendrick wants her fans to know that she's also surprised by the success of "Cups (Pitch Perfect's When I'm Gone)."

The single has been firmly planted on the Billboard Hot 100 for well over a month, and the YouTube video has more than 43 million views -- which isn't too shabby for a song Kendrick learned because, as she told Dave Letterman in October, she's "a huge loser."

Kendrick learned the song, which was originally recorded by a twosome called Lulu and the Lampshades, from a 2009 viral video that was popular on Reddit. And, she says, when the producers learned she knew the trick, they insisted that it make it into the film. But no one anticipated the success of the track.

"Just need you to know that I get it too, guys. It's very very odd," tweeted Kendrick, attaching an Instagram video of herself, speechless.

The tweet was favorited more than 1,800 times.