Hopefully this is only something you've seen in the movies and have never had to experience in real life.
But if you've watched enough films, you will have noticed that when a cop pulls someone over, they briefly touch the back of the car before approaching the driver-side window.
"How can I help you officer?" is usually what is said afterwards.
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It turns out though that there is a perfectly normal reason as to why this is the case.
Taking to TikTok, user @mr.alexaa shared a viral compilation video of police officers who are seen touching the rear of the vehicle.
And according to people in the comments, they believe it's so the officer's fingerprints are on the car in case anything happens to them during the stop.
Traffic safety expert Trooper Steve Montiero has since revealed the truth in an interview with News 6.
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He said: "When law enforcement officers conduct a traffic stop, there are plenty of procedures that need to be done, not only for the safety of the violator, but for the safety of that officer.
"One of those things is proving that that officer was with that car, so when officers approach a vehicle, they touch the rear of it."
Montiero went on: "The first reason is to make sure that the trunk is closed.
"It may sound a little crazy, but you want to make sure that no one is about to jump out of the trunk and that it's properly secured.
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"Touching the rear of the vehicle puts the officer's fingerprints on that car, showing that he or she was there with it.
"In case the driver decided to flee the scene, or if something happened to that officer, it ties both the vehicle and the officer together."
He added: "This is just one of the many things that take place during traffic stops to ensure everyone's safety."
Since it was posted, the video has been watched millions of times, with hundreds of viewers piling into the comments to share their thoughts on it.
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One user said: "I am a law enforcement student in Arizona, and we were taught to do that not only for the finger print but to make sure the back is closed."
Another echoed: "We also do it to make sure the trunk is closed, so no one pops out to shoot us.
"At least that's what I was taught at the academy over 20 years ago."
Anish Vij