the only sure thing is to use someone who is clean's urine. its been my experience that they don't watch you go. in the past, i've had a clean friend piss in a glass bottle for me, secured it up underneath my balls (painful and degrading but worth the negative test!) at least a couple of hours before the test to allow the urine to regain full body temperature, and just poured their piss into my sample cup. i can't say i trust any of the other methods.