It's now become a very cool tradition. Bono, Glen Hansard and other Irish musicians hit up Grafton Street and have an aul sing song.
This year The Script, Hozier and Kodaline joined the two lads, while The Script periscoped the whole thing.
Is there anywhere in the world where this happens? The biggest names in music entertain last minute shoppers in the middle of a busy street and probably raise a few quid for charity.
Really brilliant stuff.