Nothing says "I'm Dreaming of a White Christmas" like Gundams battling in the snow!
And Gon and Killua are full of Christmas Spirit! (Well no they're not, but you can THINK that!)
Finally, for now, brotherhood Uchiha Style (and they'd both be on the "naughty" list)!
Will post gifs later!
Edit: ...or maybe not. Christmas was just too much for me!