Day 9 is a song that makes you happy, which is a lot of them. I’m gonna go with Rhiannon Giddens’s medley of two Gaelic tunes, “‘S iomadh rud tha dhìth orm / Ciamar a nì mi ‘n dannsa dìreach.” Incorrectly identified as “Mouth Music” (that’s a different song of hers), it’s presented below from when she appeared on Austin City Limits, and it always brings a smile to my face, from the way she bounces during the second part to her percussionist who is looking incredibly cool and dapper in a suit.
KRAD's Inaccurate Guide to Life 
http://www.celticlyricscorner.net/macaskill/mor.htm
Lyrics – it’s a wedding song
http://www.celticlyricscorner.net/puirt/ciamar.htm
Lyrics – about dancing but mostly about the tune
I cannot help it, I had to look it up.
Retired, but been a professional editor, researcher, etc for decades. I can’t stop.