Step 1: Measure fabric
[My rectangle measured to be 140cmx102cm, but I would have liked to make it longer, to maybe 150cmx102cm.]
[Also, apologies for the terrible state of my fabric- I found it at the bottom of my fabric stash and I couldn't wait to get started!]
Step 2: Cut the slits
I was really, really lazy and folded my fabric twice into a quarter, and make the cut once.
Step 3: Wear it!
[I'm entering this in the I Could Make That contest, so if you like this instructable, a vote would be greatly appreciated :D]