If you're looking for an easy and inexpensive costume to put together, go with Bart Simpson. This wise cracking underachiever will be the life of the party. Best of all, this costume is comfortable to wear which is more than can be said for those requiring masks and gowns.
Wear a short-sleeved red t-shirt, blue shorts and blue tennis shoes, and you're halfway there. If you don't already have these things, shop a thrift store or yard sale where you can pick them up cheap.
Apply yellow body paint to your face, arms and legs to get that famous Simpson flesh tone.
Spray temporary yellow hair spray in your hair, even if you're blonde as the bright yellow will add a special effect to the costume. Then when your hair is dry, spike it. If you hair is too long to spike, buy a wig at a local thrift store and use the same process.
Borrow a skateboard if you don't have one, or pick one up cheap at a garage sale. Bart Simpson never goes anywhere without his skateboard as it's his main mode of transportation.
Get into character and quote Bart Simpson phrases throughout the night. His most famous are "Ay caramba", "Eat my shorts" and "Don't have a cow, man." Take it a step further and tell people about the time Miss Krabappel made you write, "I will not make flatulent noises in class" or "A burp is not an answer" on the chalkboard 100 times.