…but don’t expect miracles. I sleep in XXXL cotton t-shirts, and I have yet to see one shrink a whole bunch, even after being washed in hot water and dried on Hot. The manufacturers mean it when they say “pre-shrunk”, because if they sell a t-shirt advertised as “pre-shrunk” and then it shrinks, they’re going to be short one unhappy customer.
You could try turning it inside out and taking in the seams, or get someone else to do it who knows how to sew. But again, don’t expect miracles.
Buy another shirt? Or is the one that Stone Cold Steve Austin autographed?
Liquid nitrogen, that’s used as a farm fertilizer, shrinks fabric tremendously. I’m sure you could find the right mixture to get the desired effect. A friend of mine shrunk a dollar bill to 25%. Now that looked cool. But I haven’t actually tried doing it to my clothes.
Boil it for 15 or 20 minutes. That’s how they used to do it years ago. When it cools, put it on and wander around in the hot sun until it drys for a form fit. The old cotton canvass jeans used to be baggy, so people would soak them, put them on and walk around in them until they dried and shrank to fit their bodies.