"UPass". I have used it for years multiple times. I don't know of any other product with a longer track record. It's so damn good, that if you search for it online, you will only find sites saying that it's bunk and to buy their product instead. Don't believe that shit. I've used this stuff for YEARS and it tests out every single time.
$15-20 bucks on Ebay/Amazon when it is available. It's not always available by sellers, however. Otherwise have to find it locally at a head shop.
Get the temp right and it's clean piss!
It has a temp strip tape attached to the bottle so you know the temperature is correct. An easy way to get it exactly right is wear a pair of tighty whities, stuff that little bottle up in your crotch securely with them tight ass undies, and in 20 minutes your "piss" is the perfect temperature matching your body. Walk that bad boy into the bathroom, pull it out of your crotch and pour it in the cup and you are good to go brother!
I had a day where my vehicle was hit by another while on the job, so I walked around with that bottle up in my crotch for the whole day prepared to pass that drug test coming up randomly afterwards.
I still work there today