Step 1: Lay t-shirt flat and find vertical (lengthwise) middle
Step 2: Cut lengthwise slit up t-shirt's middle front side
Step 3: Cut the arms of the shirt off.
You're Done! Now you have a cute vest to wear with a tank and a perfect pair of jeans!
Note: I angled the bottom of my vest for a more interesting look, but feel free to leave the bottom edges straight or get wild and fringe them!