5. Swapping urine samples. Whether they use a friend's clean urine, synthetic pee, or even freeze-dried urine purchased online, some teens try to pass off foreign samples as their own, says Levy. The biggest tip-off is temperature. "Anything significantly lower than body temperature is suspicious," says Dasgupta, which is why some have tried to shuttle samples in armpits or taped to thighs to keep them warm. Possibly the oddest trick of all is a device marketed to those trying to beat witnessed drug collections, says Wu: a sort of prosthetic penis called the "Whizzinator" that claims to come equipped with clean urine "guaranteed" to remain at body temperature for hours, with the help of special heat pads. "Believe it or not, [the prosthesis] comes in different colors," says Wu.