JACKSONVILLE, Fla. — A Florida gas station owner has placed a sign in his store asking customers not to warm urine in the microwave.

Parul Patel says he’s become “sick and tired” of people walking into his BP gas station and On the Fly convenience store in Jacksonville to warm their containers of urine. The store is within walking distance of two labs, though one says it doesn’t collect samples for drug tests.

Patel tells First Coast News the people “walk in off the street, microwave their urine containers then leave.”

Warming urine from someone who hasn’t taken drugs is seen by some as a way to help pass a drug test.

Patal says a woman became aggressive a few months ago when he asked her not to warm urine. She asked to see a sign that says it’s not for that purpose. So he made one.