You will need a t-shirt, scissors, and a needle and thread.
Lay the t-shirt flat on the table and cut about half an inch off the sides, also removing the sleeves. When you lay it out, you should have a long rectangle with the neck hole in the middle. Keep the sleeves and the two long strips that you’ve cut off, you’ll need these later.
Cut open one of the sleeves along the seam, which will leave you with a rectangle of fabric. Cut the biggest circle you can out of this fabric. It should be bigger than the neck hole. Next, sew this circle into the neck hole so that you have a pouch. This is where the package goes. Now your loincloth should look like this:
Tie the two long strips of fabric from the sides together, or if you’re feeling ambitious, sew them for a more professional look. This is the “belt.”
To wear, position the neck hole pouch under package so that it feels comfortable. Hold the ends of the rectangle up in the front and back and then tie the belt around your waist, letting the ends of the larger rectangle fall down to cover the front and rear. Adjust as needed.