Step 1: Make the rig
You will want to dig this in the hottest part of the ground you can, not shade.
Step 2: Pee in your hole
Once you have this up and running for real, you can take the poncho off and the container out any time you have to pee.
Might as well put it to use than peeing on a tree, dont you think?
Step 4: Place the plastic over the hole
A side note is, it is a good idea to use some of the soil to cover the edges, thus sealing it from critters and such, and keeping it weighed down a bit on the edges.
Step 5: Place a rock/soil in the middle of the poncho
Step 6: Wait
You won't get a full waterbottle, but you will get some, which isn't such a bad deal, concidering you dont have to put any effort into it other than building it.
Step 7: How this works
What happens is, the sun's heat evaporates only the pure water from the moist soil. The water vapor rises to the poncho where it condenses into water drops. After a while of this, the water drops build up and roll down the the middle of the poncho where they then fall into the container.
This gives you pure water from your urine.