I have a story that happened to me that SOUNDS like BS, but isn't.
On New Year's Eve of '07, I went to try to check myself into an Outpatient class (I was seriously fucked up and it was like 11 pm during a blizzard and I drove myself to the hospital). Obviously after telling them what I ingested (an awful lot of heroin, benzos, cocaine and MDMA that was likely cut with amphetamines), they admitted me to the ER.
They admitted me, but on the crazy ward, not the detox ward like I'd been on before. I later found out that they told my mom they weren't sure why I would be lying, but the UA and blood test came back negative for any drugs.