I don't want to go home!
I HATE GOING HOME.
James, Remus....save me.
You could always... decide not to go home. I'm telling you this as a brother; it's not like they really want you around.
My best bet for you would be feigning an illness.
Anyway, I don't want to go home either. I'd like to experience a Hogwarts Winter Holiday, and if I'm here they might not order you back home.
If I can convince them to let me stay.
I second the motion. Sirius, your parents couldn't say no to a formal invitation from a nice, respectable family like the Potters, could they? James, get your Mum to write his Mum.
(See, the trick is to get the parents talking to each other on our terms. Always results in good things, as long as we keep tabs on them.)