Niall Horan seemed to have had a blast with Jimmy Fallon when they played a round of The Instant Song Challenge.
The game involves making up songs on the spot based on titles that fans send in.
Niall can barely contain himself with laughter as they begin with the first song ‘witness the fitness’, and he even joked that it could go to number one.
They also sang ‘Quicky clicky pens’ and ‘Stepping on my toes’.
You can watch the hilarious clip below.