All you need is an old pair of shorts, fabric paint, a paintbrush, and a stencil (i made mine out of paper). I chose to use blue and red paint since my shorts were so light in color. If you have darker denim, I'd recommend using white and red paint.
I started with the stripes.
I wanted a rougher look to mine, so I didn't worry too much about making the lines perfect.
Then, trace your star stencil.
Paint around the lines.
Let them dry overnight. I washed mine in the sink the first time in case they bled some of the paint.
Here is the finished product! Pretty patriotic, huh?
If you have any questions feel free to post them in the comments!