Fun. have taken over radio and iTunes with 'We Are Young,' and now the New York band is taking YouTube by storm as well. That's a sign that you've made it -- when strangers are covering your songs! This acoustic rendition is particularly charming.

Performed by Alex G. and Jon D., the track is a mellower, softer version of the original. Instead of Fun.'s version, which has frontman Nathan Ruess singing the entirety of the song with Janelle Monae featuring on the bridge near its end, Alex G. and Jon D.'s ballad allows both vocalists equal time to shine. Alex's strong mezzo-soprano is accompanied perfectly by Jon D.'s gentle vocals and a pal's guitar.

The duo are YouTube sensations individually, so we can only imagine how much they'll explode by collaborating together. Alex G. has over 100,000 subscribers to her own channel, which also features covers of Paramore and Gym Class Heroes. Jon D., a viral sensation for his silly parody clips, will likely shock fans with his natural ability to sing beautifully without being goofy.

If you dig the tune, it's available for download in full on iTunes. Do you think Alex and Jon will be the next Karmin-style sensations?

Watch Alex G. + Jon D. Perform 'We Are Young'