Proof that DNA is the go-to answer for all of life’s mysteries: A couple in upstate New York has used the test to prove that they were badly mistreated by a waiter at Chili’s.

According to a story on abc7.com, Ken and Julie Aluzzo Yerdon went to eat at the restaurant in July of last year. They didn’t have a great experience; they told the waiter, Gregory Lamica, that their food was undercooked and the chips never arrived.

Before they left, they asked for to-go drinks. In the car, they noticed something that looked odd in one of the cups. Ken Yerdon removed the lid and said he saw evidence of spit in the drink, adding, “It was really bad.”

He then drove back to the restaurant and asked to talk to the waiter, but he wasn’t allowed to.

“They basically just wanted us to be happy with a couple of coupons and our money back,” Julie Yerdon told ABC News. “That just wasn’t going to work for us.”

After calling the police, the couple sent the drink in for testing, because they were concerned about their health. Officers arranged for Lamica’s DNA to be taken to see if he had indeed spit in the cup.

The results were conclusive: He was guilty. Lamica then confessed to doing it and was charged with disorderly conducted. He pleaded guilty and was sentenced to a one-year conditional discharge and a fine of $125.

The couple is now suing the restaurant and the waiter for negligence and retention of an incompetent employee.