Most guys would think that this is girl stuff because it's braiding but it kinda fun when there's nothing else to do well here are pics of it completed(pic1) and of its final knot(pic2).
Step 1: First Stitch
take two peices of string the same length and cross them at their middle. then take the two bottom (yellow in my case) strands and cross them over the top to look like my second pic. take the other strands and cross them over the first yellow and under the second so it looks like pic three. pull tight.