Police are urging people who work in drive-through windows at fast-food restaurants to be wary of a fast-growing, Internet-fueled prank that involves customers who yell "Fire in the hole," then throw drinks into the faces of workers before driving off hooting and laughing.

In many cases, the stunts appear to be recorded -- usually on cell phone cameras -- so they can be posted at video-sharing sites like YouTube and Ebaumsworld, where hundreds of such clips are can be viewed.

The prank appeared to be occurring in other parts of the country until Friday night, when a liquid was thrown into the face of a young man working the drive-through window at a Subway sandwich shop on Route 30 on Jacktown Hill in North Huntingdon. It was caught on one of the restaurant's surveillance cameras and police are taking it very seriously.

"This is a big thing," said Patrolman First Class William Sombo, who is investigating the incident, which occurred at 10:33 p.m. "This is an assault."

In most of the videos posted on the Internet, drivers throw drinks they have just purchased -- colas, milk shakes, etc. -- back into the employee's face. In the incident in North Huntingdon, however, the liquid that was tossed had been brought to the window by the driver.

"The deal with the 'fire in the hole,' just throwing a drink back at them, that's disorderly conduct and harassment," Officer Sombo said. "But this was right into his face, and it was a substance that burned his eyes. [The victim] feels, because of the smell and the taste, that it may been jalapeno juice, hot sauce and some other kind of drink mixed with it. It was not the drink [the driver] ordered. He brought something."

An Internet search showed that some pranksters have been sharing a preferred recipe for "fire in the hole," which is made of pepper sauces and alcohol.

"It would be similar to getting pepper sprayed," said Officer Sombo. "The short-term effect would be 10 to 15 minutes, sometimes longer depending upon how big of a dose you get. But if it happened to be a cleaner or chemical, you could have eye injuries."

Officer Sombo said the local victim, who asked not to be identified, suffered some discomfort and burning in his eyes, but he was all right a short time later.

"The point is he didn't know what it was and he didn't know what to do," Officer Sombo said.

Police were searching for a 2000 series Dodge Dakota pickup truck, red with an extended cab and a black tarp over the back.

The driver was described as a white male, in his late teens or early 20s, wearing a white baseball cap and bright yellow shirt with bold, black lettering. The first letter, visible in the surveillance tape, was an N and the last was an A, and they appeared to be Greek letters similar to what a fraternity might use.

"We can see him, but we can't make it out," Officer Sombo said. "If somebody sees the video, they may know this clown."

If found, Officer Sombo said, the driver would face charges including assault, harassment, disorderly conduct and reckless endangerment.

Officer Sombo said police are sharing information on such incidents and cautioning workers at restaurants that have drive-through windows.

"They need to be aware of this and pay attention when the individual pulls up to the window," he said. "Make sure you're observant, get a good look at the person, and if anything happens, try to get a license plate."

Most restaurant managers and young adults interviewed by the Pittsburgh Post-Gazette last night said they had not heard of such a prank or seen the videos on the Internet.

Robin Schnepp, 18, of Kennedy, who works at a drive-through for a restaurant at Robinson Town Centre, said she couldn't imagine anyone she knows doing such a thing.

"I wouldn't find that funny," she said. "I think that's rude."

Ms. Schnepp said she had never been advised by restaurant managers to watch for such pranks or what to do if they happen. And she had never experienced anything like it.

"Some people are mean," she said of working at the drive-through, "but I've never had anyone throw stuff back at me."

Will Perez, 25, of Baden, said he had seen something similar on a video, showing skateboarding stunts and pranks emulating the movie "Jackass," about seven years ago. He admitted that he saw the humor in it, "but I wouldn't do it," he said.

"I was a lot younger when I watched it, and me and my friends thought it was hilarious at the time," he said. "But, obviously, I've grown up. ... I have more respect for people. I wouldn't want people coming into my work and messing with me, so I'm not going to mess with anybody."

Ryan McConnell, 22, of Aliquippa, said he first saw a "fire in the hole" video online this past weekend.

"I laughed," he said. "I couldn't help it. But if that was me in that position, it wouldn't be too funny." Asked if he could imagine being in a car with friends and doing something like that, he said no.

"I'm more reserved. I wouldn't do that," he said. "But it depends where I'm sitting in the car. If I'm driving, no way. But if I'm just a passenger ..."