A "wet Willy" practical joke landed a man in jail over the weekend.

Riley Swearingen, 24, was getting on the Late Night Express (also called the "drunk bus") in Mankato after the bars closed early Saturday when police say he walked up behind a police sergeant, licked his fingers and poked them in both the officer's ears, the Mankato Free Press reports.

Swearingen, who was on leave from a U.S. Air Force base in North Carolina, was charged Monday with fourth-degree assault on a peace officer involving bodily fluid (a felony), fifth-degree assault, and disruptive intoxication, KTOE reports, but Swearingen quickly agreed to a plea deal, pleading guilty to a lesser charge of disruptive intoxication, a misdemeanor.

According to Minnesota statutes, fourth-degree assault of an on-duty peace officer is a gross misdemeanor – unless a bodily fluid or feces is involved. If that's the case, the charge is bumped up to a felony, with a maximum penalty of up to three years in prison, and a fine of up to $6,000.

"I thought it would be incredibly funny to give a police officer a wet Willy, to which I was sorely mistaken," Swearingen said, according to the Free Press. "I'm incredibly sorry for what I did. I never thought I would be going to jail for the weekend."

Officials said alcohol played a factor in the not-so-funny "wet Willy" joke – Swearingen's blood alcohol content was 0.18, reports say.

Swearingen was sentenced to three days in jail and was told to pay $77 in court costs, according to reports.

This embed is invalid