There is nothing worse than strolling back over to your car and spotting something wedged underneath the wipers.
Is it a note apologising for scratching your paintwork? A ticket from the traffic warden? Panic mode immediately sets in.
But it turns out there is something even more worrying that could be left on your car - an almost illegible scrawl on a grubby-looking sign.
They explained that they had left the car parked up for a few hours while they headed to a concert together in the capital.
But when they returned, the pair found a mysterious message had been 'wedged in the passenger side window'.
The post included a picture of what appeared to be a piece of card, with an array of confusing numbers and letters on it.
It seemed to read: "Zirakmantk21, Gum Volo."
If you're not fluent in gibberish like me, there's a good chance that you were just as baffled as the Reddit user.
They continued: "There was no damage to her car and it’s not a license plate, does anyone know what it means or could be?"
There's nothing like turning to the good people of Reddit during a minor crisis.
People flooded the post with their theories of what the message meant, which ranged from comical to downright concerning.
One joked: "Don't worry, it's just a secret message from aliens. Time for an extraterrestrial car wash!"
Another said: "Check the car for bumps and scratches. Someone probably hit it in front of some bystanders, had no intention of leaving their actual details but wanted to look like they were doing the right thing."
A third added: "Looks like the car got caught up in an international spy thriller! Better check for any hidden cameras too!"
A fourth chimed in: "The top line is a Snapchat username. It autofills very quickly."
Someone else even said they had found a 'really,really similar' note on their car in London recently too - which only added to the mystery.
But the most compelling argument came from a user who used the wonders of the web to aid their investigation.
They wrote: "It’s in Uzbek, according to Google Translate. Zirak mantk means 'intelligent logic' (I guess zirakmantk21 is a username somewhere).
"Gum uolo means 'I’m sorry' - are you sure there’s no minor damage to the car?
"For what it’s worth, 0511 on the number at the top of the card is the area code for Hannover."
Sadly, the original poster isn't any closer to deciphering the scribble - or why it is written on a sheet of card from Germany.
They explained they had added the username on SnapChat and asked about the message, but hadn't received a response.
I think they might have to call in Sherlock Holmes for this one.Featured Image Credit: Getty stock image/Reddit