DOT AND WAKKO WARNER:
Dot: wear black leggings, black turtleneck, and a pink skirt. Cut ears out of black felt and sew/glue/pin them onto a headband, add a big yellow flower to headband, make a tail out of coat hanger covered with black material, and paint your nose red with make-up. Add white gardening gloves to finish the look.
Wakko: wear black sweats or leggings, baggy blue sweatshirt, and a red baseball hat. Cut ears out of black felt and sew/glue/pin them onto the hat, make a tail out of a coat hanger covered with black material, and paint your nose red with make-up. Wear white gardening gloves to complete the look.
MARVIN THE MARTIAN (from Bugs Bunny): Tape a brush to the top of a motorcycle helmet or a green hat. Wear a black ski mask. Wear red sweat suit or clothing. Wear a green skirt or make one out of cardboard. Get a ping pong ball gun or any space gun and carry it. Wear white shoes to complete the outfit.
UNDERDOG: wear a red sweat suit and draw a big U on the front of the sweatshirt with magic marker, sharpie, or fabric paint. The U should be white, but other colors will work. Wear a big blue cape, which can be done by using a big blue towel or table cloth. Then color your nose black with make-up or face paint and add ears by pinning black socks to a headband or baseball cap.
TEEDLE DEE AND TWEEDLE DUM: best done as a pair. Wear red pants, high waisted if possible, a yellow long sleeved shirt, red beanie or a red baseball cap if you can't find a beanie, and big blue bow tie. For added effect, paint your hair orange with costume hair spray (make sure it's temporary and will wash out) or make an orange wig using yarn.
BEAVIS AND BUTT-HEAD:
Beavis: wear short grey shorts and a Metallica or Slayer t-shirt (or any heavy metal shirt), and white grungy tube socks with black shoes. Put red zits on your face with make-up, make hair look greasy and messy with hair gel, and feign an underbite.
Butt-Head: wear short red shorts, an AC/DC t-shirt (or any heavy metal shirt), and white grungy tube socks with black shoes. Put red zits on your face with make-up, make your hair look greasy and messy with gel, squint and say "uhhh" a lot.