This is only a semi-lighthearted thread. I'm Australian, DH is English. So, like I said, only semi-lighthearted 
How the hell do you civilly manage/encourage sporting team allegiances with DCs? The thought of my DSs supporting the England Cricket Team makes me want to throw-up/cry/both, but DH is insistent (they have Australian citizenship, dammit! They could have that retracted if Australia House found out, I'm sure!). We went to an England v Australia under-19s rugby league match yesterday and I was quietly jubilant when DS1 (2y 6m) wandered off during God Save the Queen but was very enthusiastic about Advance Australia Fair.
They're only tiny still, but I can see DH's and my banter through gritted teeth about our boys' sporting teams when they're older getting serious...