Tarn is t-shirt yarn.
1. Flatten your clean plastic bag.
2. Cut off the handles and bottom seam. You can't use them for plyarn. Save them and use instead of packing peanuts or fuse them and make something new.
3. Open the folded sides, then fold from fold to fold a few times.
4. Cut bag in 1" strips.
5. These strips form loops. Put loop A inside of loop B. Put one side of loop A through the other side of loop A. Gently pull. This is how you join them without tying knots.
6. If one breaks, use it to join 2 other loops with. Put it through 2 loops and tie a knot with the broken strip. Now 3 loops are joined.
7. Now make a ball of plyarn. Knit it. Crochet. Weave it. Gift it.