There are all kinds of urban legends out there about drugs and drug use. Here’s one you may not have heard before: Your tongue can turn green from smoking marijuana.

Does it sound ridiculous? It should, because there’s no scientific evidence whatsoever that smoking marijuana can leave your tongue tinted green. It’s just an idea that was made popular because of a badly designed cover on a 1986 handbook that told the authorities how to recognize marijuana users.

That doesn’t stop police officers, however, from claiming that they had probable cause to make an arrest or perform a warrantless search on someone’s vehicle because the suspect had a “green film” on their tongue. To be fair, many officers are told to look for a green tongue as part of their training (thanks to that old handbook), but it is rather curious that there’s never been an actual photo of a green tongue put into evidence.

The “green tongue” phenomenon isn’t unique to any one particular area. Defense attorneys around the nation have heard of it before. So have advocates for marijuana reform. As stated by the executive director of NORML, “The science behind marijuana consumption turning your tongue green is about as sound as the science behind the earth being flat or that lying makes your nose grow.”

The reality is that an officer who is determined to find probable cause for a search or a drug arrest can probably find one — even if it is based on something wholly imaginary. It takes an experienced defense attorney to protect your rights when you’ve been charged with a drug crime.