A Dunkin’ Donuts worker has been arrested after an Illinois State Police officer discovered a “large, thick piece of mucus which was later confirmed to be saliva” in his coffee, authorities said.

The incident took place at 10:20 p.m. on July 30 when an Illinois State Police (ISP) District Chicago trooper purchased a large black coffee from Dunkin’ Donuts on Archer Avenue in Chicago, ABC News reported.

“Due to the coffee being extremely hot, the Trooper removed the lid from the top of the cup to cool it down,” the Illinois State Police said in a statement.

It was at that moment when the officer discovered the saliva floating in his cup.

The ISP immediately opened an investigation into the incident, which concluded with the arrest of Vincent J. Sessler, a 25-year-old Dunkin’ Donuts employee.