Why spend money on wrapping paper, when your town has a plastic bag ban, and every time you buy more than will fit into your re-usable bags, you get paper.
Here's What you do... cut the paper bag so that it will lay flat.
Choose no more than 5 coordinating colors, and get a ruler (unless you want to free-hand it)
Come up with a design.. Stripes are fun, and using a combination of different widths adds a new design element than just stripes. You could also do polka dots in different colors and sizes, or big swirly lines, etc. When you are doing something that isn't as rigid as stripes, it will take less time to color the paper.
I used the width of my ruler as a spacing guide, that way you can just roll it over and mark along the width of the paper. You mark with one color, then two times with the next color, that way you get the variance of wide versus thin stripes. Go back after and color them in.
Voila, you're done! You can use the paper for any holiday, birthday, wedding, or other gift giving reason.