Jimmy Fallon Challenges Niall Horan to the Instant Song Challenge

Niall Horan, seriously, has the most ADORABLE giggle.

The former One Directioner crashed Jimmy Fallon's show the other night and the two got a little creative.  The two got embroiled in an "Instant Song" challenge where they had to whip up a radio hit using random song titles thought up by members of the audience. 

So, if you wanted to know how Niall would sing a song about stepping on toes, this is your video.  Enjoy!