ha, my friend, you and anyone in your boat are screwed.  there's just no way around it.  or...

if you know for a fact that you'll be able to walk into the bathroom alone, and be alone, fill up some waterproof small bottle with a drug-free friend, your sex, your age, your general weight (non-diabetic or diabetic depending on if you are or not), etc... Fill up a bottle, like a larger pill bottle, or whatever can hold a small cup worth.  dont feel like you have to fill up that whole cup!  also, you could duct tape the crap out of a zipper-ziploc baggy, making sure it will be sealed, and then tape it to your stomach or groin area, and then undo it all carefully and fill the cup.  but, make sure it's just a drug test, and not some physical where they are going to pat you down!  

really, you're screwed.