I don't have the link handy, but a football player at Ohio University (not The Ohio State University) used his girlfriends urine for a drug test and discovered that he was pregnant. He was immediately suspended for 2 years by the NCAA. I think the story also mentioned that his girlfriend did not know. That was not a good day for that young man! If they had found drugs in his system, which I think very likely since he used his GF's urine, he would have gotten a one-year suspension, at least for performance enhancing drugs ..... I think less for pot.
I used to run trucking companies. When we first had to implement drug testing a driver from another company was at the same clinic we used to collect the samples. The nurse thought he was acting nervous so she stayed outside the collection room. After a few minutes she heard a scream and opened the door. The guy had duct taped a baggie of clean urine to the back of his man berries. When he pulled the tape off his skin came with it. He needed surgery. Dude had the nerve to apply for worker’s compensation.