Cardboard box with wrapping paper glued to the outside, head and armholes cut. Big bow in front. A present...
Cardboard box, paint in Lego primary colour, stick on painted jar lids or plastic cups cut short in same colour, cut out head and arm holes - a Lego block. Wear same colour trews and top underneath. Optional - Lego person head in yellow on top.
A mime - black leggings, striped top, face whitened, mime-looking makeup (eyes, lips, cheeks).
Stick figure - requires white sweatpants, white sweatshirt, black ribbon. Sew the ribbon on front of each leg of the sweatpants, one strip up the middle of the sweatshirt, one strip in front of each arm, whiten face and draw a black circle from chin to forehead. Ribbon sections all meet at lower abdomen and at neck.You can sew ribbon on the back in stick figure shape too.
Spider - dress DC in black, head to toe. Stuff six long black socks with whatever fabric/ other socks/ tissue paper you have to hand, attach stuffed socks to the black top to form spider legs. Use one long piece of string to tie the end of each spider leg and the wrists of the DC so the legs move up and down when the arms move. Leave plenty of string between each 'leg'. A little black beanie hat would look good with this.
Snail - get a long roll of brown paper. Crumple it a bit, then fold to about a foot wide. Roll it into a snail shell shape. Glue the end to the roll, or staple. Attach fabric straps to the shell with stapler or hot glue to go over DC's shoulders and cross in front. Dress DC in brown, and make snail antennae with a hairband, pompoms, ping pong balls, etc.