As the big showdown with England on Sunday approaches, all four provinces will be united (along with France, Wales, Scotland and Italy) in their desire to see England lose.
But with the squad featuring players from all provinces, local rivalries are not forgotten.
This rather foul-mouthed sketch parodies fans of each province - from the 'I played with him at Rock' Leinster supporter to the sheepish Connaught man.
Download the brand new OffTheBall App in the Play Store & App Store right now! We've got you covered!
Subscribe to OffTheBall's YouTube channel for more videos, like us on Facebook or follow us on Twitter for the latest sporting news and content.
