It really is my lucky day—another Smile Song resource has come our way! This one is from INSYG, and it's a really neat arrangement of the cheerful Pinkie Pie ballad.
INSYG has written a four hands piano version of Smile, so you can play it as a duet with a friend and have plenty of reasons to smile together. Grab a piano and a partner and give it a try! You can find the sheet music here.
Thanks for sharing your talents, INSYG!