I was browsing around a HP website and I found this...
I don't think I've seen it posted here before...
11 Ways to Use Harry Potter to Annoy a Twilight Fan
1. Steal their copy of Twilight and replace it with one of your Harry Potter books in a Twilight dust jacket.
2. Tell them that Edward is a "hand-me-down" because the Twilight movies got him after the Harry Potter movies were finished with him.
3. List other "hand-me-downs" from the books, like the last names of Black and Clearwater...
4. State that you think Edward would be hotter if he had a lightning scar on his forehead.
5. "Accidentally" call Edward, Sanguini.
6. Explain in detail how any wizard can possess all the gifts (seeing the future, reading minds, etc.), that a vampire would only have one of.
7. Whenever they mention Jacob Black, innocently ask if they meant Stubby Boardman.
8. Say that Bella and Filch would make a cute couple.
9. Flinch whenever they say "Edward" and tell them to say "You-Know-Who."
10. Whenever they describe the vampires of the Twilight series (sparkly skin, no fangs, etc.), contradict them, and tell them what "real" vampires, out of Harry Potter, are like.
11. Explain how Twilight werewolves are really Animagi, and ask whether they've registered with the Ministry.
http://www.mugglenet.com/funlists/twilightvspotter.shtml
Well, it made me laugh, anyway!
And if all hand-me-downs looked like this... well, words fail me...