I can’t sum it up any better than with this video.
In case you need a reminder of what last year’s Christmas scene was like, see this video for the 1st Annual Nerf Gun War.
If you listen closely, between the "pop pop pop" of the nerf guns, you can hear Noel playing and Alex screaming "Not near the Chihuly painting." There is a tender moment at the end where Cousin Cooper helps Finn load his gun and pump it with air before shooting relatives. This is what Christmas is all about.