Pull these easy looks together using things you already have in your closet or lying around the house. Bonus: these are all cheap and environmentally friendly.
Solo cups will transform you into a Lego:
Just paint a box and cut holes for your head and arms, then glue the cups to the front. Write "LEGO" on the cups if you really want your friends to get it without thinking.
Source: creatingreallyawesomefreethings.com
Use a paper bag to make a safari vest:
And cut up a paper towel roll for binoculars; full instructions from Real Simple. The example shown is for a child, of course, but you could size up for an adult. Warning: costume not ideal for rainy weather.
Source: realsimple.com
If have even an ounce of hipster in you, you probably have what you need to make a Where's Waldo costume:
All you need is a striped shirt, red hat, and big glasses.
Source: inhabitat.com
An old hoodie can become an easy (and cozy) animal outfit with some white felt or paper. A wolf, for instance:
If you have matching sweatpants you can stick a tail on them. Martha Stewart, Halloween master, provides the instructions.
Source: thecraftsdept.marthastewart.com