I made this out of my old t-shirt. Make sure there is some stretch in your chosen t-shirt before cutting it up or else it won't work when you pull the strips for effect.
Cut off the arms, the bottom hem and the hem around the neck! Make sure there is enough shoulder space In order to cut of the neck hem.
From the bottom, start cutting strips upwards to the desired lenght.
When this is done, pull the strips away from the top really hard so that the material stretches.
Then you can add ransom cuts into the shoulder parts and use pins were you feel suitbable :)