What you need:
All you have to do is tape, staple, or glue the Smarties to your pants and you're Smartie Pants.
Quick and easy to do. It will definitely win a costume prize.
Thanks to an anonymous submitter for this great idea!
Another Idea
You could be a smarty pants. Wear any shirt and pants, but tape smarties the candy to your pants.
Thanks to Maggie for this addition.
Another Idea
Once I saw a mother that had dressed her two little girls up in bright colors and then taped the candy "Smarties" (still in the rolled up wrapper) onto their pants and then made a sign that said "Smartie Pants" I thought it was cute.
Thanks to Kristina for this addition
Another Idea
Wear a pair of jeans and fasten SMARTIE packages to the jeans and VOILA! You're a Miss Smarty Pants!
Thanks to Kylie for this addition
Note: In Canada, Smarties are candy coated chocolate candies similar to M&Ms in the USA. In the United States, Smarties are a sugar-candy similar to "Rockets" in Canada.