I'm having a party and I have no idea what to do. Any ideas?!

Best Answer - Chosen by Voters

Oooooo fun!!!
I planned a Halloween party myself once and although it's a bit stressful at first-it's a lot of fun when the party day actually arrives. Here's some things which may help you...
If you are having trouble choosing a theme between black and white or masquerade, I suggest if you are having a black & white ball, ask the guests to make sure every thing is black/white in case the weather is chilly and they bring different coloured jackets which will drown out the hostess' dress.
Masquerade sounds like a lot of fun but you'll need to make sure that the guests will be keeping their masks on for the whole party (masks can be a little uncomfortable for a while) and that everyone has unique masks and outfits in case of mistaken identity.

Food/drink: Have yummy sophisticated food that won't clash with your theme (and budget!). With 40-50 people, you might want to think about getting a catering service in rather than cooking the food all yourself.
You can also incorporate food into a really funny, silly game; eg. Sandwich Roulette-Let your guests choose a sandwich out of an array of sandwiches with one sandwich with DISGUSTING fillings. The person who picks it MUST eat it!!

Things to do: Dancing, karaoke, technology permitting games=favourites
Charades, truth or dare, twister,spin the bottle=classics

IMPORTANT:
Welcome guests at the door
Check for an invite
Put coats and bags in a special closet to prevent theft
Offer food and drink
monitor sound levels

Get rid of:
Spills
Blocked toilets
Angry neighbours
Unwanted guests
Illegal thingees

Hope this helps and good luck for your party!!!!!

Me

You could watch movies or play mature like games. If you want you can just have a regular party with music and dancing. Hope i could help. (Pick me for best answer)

It would be helpful to know how old you are, I'm guessing a kid from what your asking and wrote?

Capture the flag! :D
My favorite game of all time!

AHH! I love masquerade balls! Or parties, whatever you call them.
Alright, I'll help you on this one. (Masquerade) Try elegant, classy music. Search through your CDs, or if it fits within your budget plan, you can hire musicians to play the violin and piano.
Ask all your guests to wear tuxes and gowns, and to show up with masks. Don't forget to show up with a dashing mask yourself. To add an extra touch, you can have someone to greet guests at the door. (Let's just call him doorman for now.) The doorman can hand out masks to any guests that do not have any, and he can say something like "Greetings. Blah blah blah this way"
Make sure you have amazing food--chocolate fountains and fondue never fail to please party guests. Cupcakes, cakes, cookies, punch, soda, stuff.
You can set up a big screen and watch movies. Is there anyone you know that will willingly face paint at your party as well?

EDIT: Guy above me has really good games!

Roulette, poker, Texas Hold 'Em.
This was my favorite childhood game and I still like to play it with my friends, but it may be a little too childish for your friends.
It's where you have everyone gather round in a big spread out circle. A Mama Fox sits in the center with a blindfold on, or in this case, closes their eyes with the masks on. The Mama Fox will have a certain item in front of her. Anyone in the circle is picked to as quietly as they can, sneak up to her/him and steal that object. The Fox claps and points in a direction when she thinks a fox is sneaking up to her. If the person sneaking up is pointed at, he/she is caught and has to return to their spot. If they succeed in stealing the item, they go back to their spot in the circle. The Mama Fox takes off her blindfold/whatever is concealing her sight and has three chances to choose whoever she thinks stole the item.

Hope this helps and that your party ends up being the best day of your life!