I chuckle most of the time. Always. But the most embarrassing thing I've done is this: we were watching OotP at my grandparents, and all the family was there, and of a sudden they started talking about how many movies there were left, and all (you know, I'm almost the only one - besides my cousin, but even so - who knows and love everything about HP and so understands it), and then my dad or someone said: "Yeah, they'll have to run, because the guy who plays Harry must be in the twenties. Oh, gosh, I piped up: "There're two more movies (before we knew about the split) and of course they're making them, there's one of the run!" Ha, I was like a tomato
Then, when I watched GoF dvd I used to play it forwards to the part in the credits they play This is the Night.
I also tried to copy Hermione's hair-do in the Yule Ball for my Prom Party, but I think mine sucked

I printed the screencap where you can see it and took it to the hairdresser. Then I stuffed it in my purse and took it with me to the party

Oh, and also, I wanted to practise my English, so the past two nights, I've been writing some lines for my sister and we played DH ...

She barely can speak English, so her pronunciation was awful, poor dear, and so her acting was, but she helped me at least! I played Hermione most of the time, and in a moment, my sis told me "Wait! There, it was just like Hermione! What you just said ... repeat that!"

She means Emma, when she says that. It's so annoying when people doesn't get the difference between actors and characters!