Buy brightly colored hooded sweatshirts in a discount store and some felt in a few different bright colors. You might also pick up some plastic googly eyes and fabric glue. Then, cut out different shapes from the felt and adhere them to the sweatshirt in a random pattern using the glue. You can finish the costume by adding felt horns and googly eyes to the hood. Wifee can add a bow to her hood to show she is the girl monster, or you can just use boyish and girlish colors for your sweatshirt and felt decoration to differentiate between the two of you.
2. Batman and Catwoman
With white chalk make a pattern on black felt for eye masks that match typical Batman and Catwoman costumes. You can look at images of the pair online for inspiration. Cut out the eyes, so you can see, and attach elastic (that you've sized to fit around your head snugly) either by sewing it or using fabric glue that has had a chance to dry completely. Batman should dress in a black sweat suit with either a paper, plastic, or fabric gold belt at his waist. For a cape, use a rectangular plastic black tablecloth, which you can find at many dollar stores or party stores. Attach black ribbon, with glue or a stapler, to each side of the tablecloth for tying at the neck. And cut a scalloped edge at the bottom to match Batman's cape. Catwoman should also wear all black, but the shirt and pants should be fitted. Leggings and a snug shirt would work. Of course, black boots are a must. Cinch your waist with an extra wide piece of black fabric or another black plastic tablecloth. If your mask doesn't already have whiskers, you can draw them on with make-up.
3. Bowling Ball and Pin
Ever see people wearing sandwich boards, two oak tag signs that are attached by pieces of ribbon and hang over your shoulders? Well, the sandwich board concept will help you make this costume. The bowling ball should wear all black, snugly fitting clothes. Then, make a giant black circle by attaching two pieces of oak tag that have been cut into semi-circles together. To hide the seam, cover the circle with a black plastic tablecloth from the dollar store or party store that is cut to fit and is glued down. Then, use white card stock to make three circles for the finger holes, which you should adhere with glue toward the top left of the ball. Create a plain black circle for your back and attach the two circles with ribbon that can hang on your shoulders. Use very strong glue to make sure the ribbon stays attached. Using large pieces of oak tag cut out two bowling pins. Use red card stock to make the typical stripes on the pin and adhere ribbon in the same way you did the bowling ball. In the end one of you should be wearing a sandwich board bowling ball, while the other wears the sandwich board pin. If you allow the pin's top to sit above your face (and you should), then you must also cut a hole for your face to come through. Of course, the pin should wear all white underneath. If oak tag is too small for you, then turn to large pieces of cardboard from the office supply or mailing supply store.
Prisoner and Guard
Those plastic handcuffs from your bachelor or bachelorette party will finally come in handy. The prisoner will wrap those babies around his or her hands. But first the prisoner will sport an all orange sweat suit that has been decorated with black numbers (use a fabric marker) typical of an inmate. The guard will wear slacks and a beige, short-sleeved shirt. Attach a paper name tag to a safety pin that you pin to the shirt. Carry around a children's sheriff's shield and a baton for effect.