Stuff the shorts with napkins and use tape anywhere you don't want paint to be.
This is how white I made mine.
Wait until the shorts are COMPLETELY dry, then tape where you want your stripes to be.
Cover with blue fabric paint.
After it is dry, use tweezers or pliers to slowly pull off the stars.
Uh oh! Well, my stickers were a fail...
If yours turned out as trashy as mine, use a paintbrush and more white paint to fill in the stars.
Carefully pull off the tape. Hmmm...my red stripes bled into the white REALLY bad! Now, I took yet another paintbrush and touched it up a bit.
And ta da! They are done! Let them dry, and you now have yourself a new pair of style forward shorts!