if you know which day the test will be, all you have to do is get a 2-4 ounce bottle, some medical tape, a hand warmer, and a few pairs of whiteys/boxer briefs.

On the day of the test, no more than 6 hours before the test (you want to be as sure as possible that this will work), get an empty powerade bottle, or something like that with a wide brim (hey, just try to make it a easy for your friend as possible). Rinse it out thoroughly, then get as much of the water out as possible. Once the bottle is empty (a few drops of water along t he sides are OK), ask your friend to piss in it. After he pisses, fill the 2-4 oz container with his piss from the powerade bottle, aand then dispose of the bottle. Close the container, and tape the handwarmer to it. Then, tape the bottle to your nuts and you should be all set

hope that helps