YOUNG BUCK MAY BE ON HIS WAY BACK TO PRISON

Young Buck could go to prison for faking a piss.

The rapper — who is on a probation — used someone else’s urine to pass a drug test … so claims his probation officer.

The P.O. says Buck came in for his drug test and concealed a plastic bag with someone else’s clean pee, and then used a tube to transfer it into a sample cup.

Turns out it’s a felony to falsify a court-ordered urine test, punishable by up to 5 years in prison.

According to court docs, Buck had been smoking weed while traveling with another rap artist. That artist is none other than Snoop.