Costume Parties: the Do's and Don't's of looking like an asshole

No matter how often I proclaim my love of costume parties, this love is almost always a lie.
I hate costume parties.
They were invented by some guy who didn't have a job and therefore had a lot of time on his hands and very little money to spend on entertainment items. So instead he would throw parties and force his friends to wear ridiculous outfits to amuse himself, because lets face it, you cannot salvage your dignity after a costume party, and if you can, you did it wrong.

The key is to go with friends. Plan your costume with other people and carpool with them, so then you know for sure that other people are wearing costumes, AND when you're walking up to the person's house/apartment/dorm/cardboard box, you don't have to feel like a complete idiot in a costume by yourself because when cars drive past, they will know you're going to a costume party and that you aren't just some weirdo who thinks its halloween 24/7.

Side Note: why is it that whenever you're in a car, the people who are walking always give you weird looks, and when you're walking, people in cars always give you weird looks?

Anyway.

See, if you don't plan ahead with friends, you run the risk of showing up and having one of the following problems:

1. You're the only one wearing a costume.
2. You're wearing the wrong kind of costume.
3. You're the only one NOT wearing a costume.

If you're the only one wearing a costume, you can just play it off like you're quirky and hilarious and you do this all the time (unless you know everyone at the party really well, in which case it either shouldn't matter that you're wearing a costume or it does matter and these people are sucky friends for making you think its a costume party. In the event of the latter, you should promptly whip out a flamethrower and set everyone on fire. Then just tell the cops that your friends all wanted to dress up as flames, and clearly it wasn't your fault for helping them.)

You could also play a fun game if you're the only one in a costume. When you show up and notice no one else is wearing a costume, don't say anything regarding the fact that you're dressed up like John Wayne Gacy meets Lady Gaga. Wait for other people to notice. When they do notice and try and say something to you about it, don't acknowledge your costume. When they say something sarcastic such as "Hey, nice outfit, retard," look at them strangely, and say "...What are you talking about? I wear this all the time. Don't you remember?"
You've instantly put the blame on them and either convinced them that you're retarded or that they're retarded. Clearly a win-win situation.

If you're wearing the wrong costume, you can somehow connect it to the theme in a ridiculously obscure way.
Is the theme pirates and you're wearing a space-suit? You're a space pirate!
Is the theme christmas and you're dressed like a zombie? you're Jesus!
Is the theme Anne Frank's attic, and you're wearing a hitler-stache and full nazi regalia?
...yeah you should probably just leave.

And if you're the only person there not wearing a costume...there's no saving yourself. You just look like an asshole who doesn't like fun. And no one likes fun-less assholes.

Oh, and please don't be the person who doesn't dress up and says "oh heh heh heh I'm dressed as myself." Or anything of that sort. You will get punched in the face. Maybe not immediately, and maybe not by anyone at that party. But I will find you and punch you in the face for saying that. Mark my words.