What would you do if you were on a bus, and suddenly a Macklemore & Ryan Lewis concert broke out?  You'll find out by watching a new Grammy promo starring the nominated duo.

In the spot, Macklemore and Ryan nonchalantly board a New York City bus, with Macklemore pulling a hoodie over his distinctive haircut.  Then, Ryan stands up with a boombox, presses play, and the duo's hit song "Can't Hold Us" starts.  Mack reveals himself, and starts hyping the crowd.  Eventually, all of the passengers are on their feet, clapping, smiling and grooving to the song.

At the next stop, the two exit the bus, as startled people on the sidewalk recognize the stars and wonder what just happened.

Macklemore & Ryan Lewis are nominated for seven awards at this year's Grammys, which air January 26 on CBS.