ya one of my friends borrowed someone elses piss, but the piss exploded under his armpit so he had piss alover and his parents killed him(not literally) cause its pretty much a given why he had someone elses piss on him... but they for some reason they still made him take the test, and he passed it... ironic no? so if i was you i would just come clean, cause parents usually get even more pissed if they find out the hard way...