Clearly I chose a shirt that needed some TLC (or a garbage can).
Snip off the collar.
Fold the shirt in half and cut off the sleeves (you get a more even cut if you cut off both sleeves at the same time).
Your shirt should look like this.
Now you will want to fold your shirt in half the other way so you can cut it to give it a sweet mullet hem.
Now you just want to use a strip of fabric (from the piece you cut off) and tie it to the back of the shirt to make it look like a racer back, wind the fabric all the way down and then tie in another knot.
Now you are ready to enjoy your tshirt! (And no this lovely model isn’t me or Astor.)