[ARCHIVE ANSWER]
Someone else's urine works great, but you have to remember a few things. They know
how long on average it takes to pee in cup, so time yourself pissing at home. They also
can’t watch unless you’re on paper. They can and do listen at the door, so make sure it
sounds right. If you are on any sort of supervision or parole, expect a mirror behind the
toilet and personnel present if they are not in fact watching.
To carry the urine, use one of those big balloons with the rubber band on the end. They
usually come two to a pack at grocery stores. Also, heat the urine to 98 degrees F
beforehand. Fill the balloon just full and place a cropped oral dose syringe into the end
and cap it. Tie a rubber band around the balloon and syringe, and there you go.
The syringe opening may have to be widened to allow realistic streaming. Replace the
rubber band on the end with a piece of string. You can hang it from your front belt loop
so that it’s positioned in my crotch next to the boys. Wear double underwear for
insulation. Also, use a digital thermometer (without the sound on) shoved down my pants
to monitor the temperature.
When you test, stay calm, drop your pants to the floor, whip out your rubber piss rocket
and fill that cup. You can let a little go into the bowl at the end for added sound effect.