I had a boring white tank and i probably wasn't going to wear it anytime soon. But i had been re-painting some wedges, and had leftover fabric paint. Then -- BRAINSTORM <3 And using a stencil from Stencilry.org (they have stencils for EVERYTHING and for free, so check em out) i made this little number!
In case the paint bleeds, put a piece of cardboard inside the tank.
Let dry for about 20 minutes, then using some tweezers or just your bare fingers (but you fingers can spread paint and tweezers leave your hands clean!) pick off all the paper pieces of stencil. You don't have to do this right away, but if you do it after the paint completely dries, the paper may be cemented to the shirt :/
(Optional) Touch up any areas you need to with a Q-tip and some fabric paint.