I haven't had to dupe a piss test in over ten years, but when I did my buddies mom worked at a medical facility and hooked me up with a bunch of brand new IV bags. They were extra long so I cut the bags down and resealed them by gluing and melting the bag halfway. I used my other buddies dads piss I had in the fridge in a empty gatorade bottle. It was some nasty dark orange piss but I knew it was clean lol.
I duct taped the IV bag to the band on my boxer shorts over my real bladder and kept my gut sucked in and looked normal, and also taped up a few hand warmer packs so I could get it in the 90-100 degree temp range. I did many test runs with plain water and a thermometer and it worked great.
The day I went in there was a long line and I had already been sitting in the parking lot for an hour, I was worried the temps would be off. So anyway, when I finally got called to the back rooms of the office building, the lady had me fill out a few forms.
Then, the sketchiest thing ever happened. She handed me the specimen bottle and then crossed her arms and just stared at me. My face turned bright red and I got the ultimate anxiety shakes. It felt like an eternity but was probably only like 10 seconds. Thats when she said oh BTW the bathroom if just over there in the hall, don't flush after your done.
I could barely walk to the bathroom, but was like oh thank god. I thought she expected me to whip it out right in front of her. Lady did it on purpose and must get a kick out of fucking with guys LOL!
I opened the valve on the IV tubing, squirted the test cup full, and even the rest that I could in the toilet without flushing. I was so nervous about what happened that I didnt get the valve closed all the way and what was left of my buddies dads piss dripped all over my crotch while I was rubbing the temp strip on the cup to make sure.
When I brought it back to the lady I was still shaking so bad I couldn't even sign my initials correct. Like, even if I was strapped with a homemade device I probably would be nervous the way she did me, and probably every other dude that walked in.
But hey I passed and got the job!
If I had to do it again, just for a regular job, maybe even a drug eval (not probation though they watch!) I would use these smaller halloween IV drink gag bags off amazon:
And sandwich them between 2 hand warmers.