We all want to make a good impression when starting a new job, right?
Unfortunately for a prison trainee over in Germany, he did the exact opposite when he sent pics of the institution's keys to his pals on WhatsApp.
Although his intentions were seemingly innocent, this could seriously jeopardise the prison's security.
As a result, all 600 of the facility's locks had to be changed - and the poor/silly sod might even have to shell out tens of thousands of Euros for the gaffe. Ouch.
The intern, who worked (past tense) at JVA Heidering prison in Germany's Berlin-Brandenburg metropolitan region, reportedly took a photo of himself inside the prison and sent it to his mates.
In the snap, he's said to be shown holding the most important key of all - the one that locks all cell and passage doors.
According to local media, the trainee, who was not named, wanted to brag about how great his new job was.
Clearly he didn't realise the implications of his actions - i.e. the key could easily be reproduced by specialists.
If this were to happen and replicas were smuggled inside, it could have led to a mass breakout of the prison, which is currently home to 657 inmates.
Although it's not known who alerted the prison about the photo, they found out and the entire prison key system had to be changed - this included the installation of 600 new locks and keys.
The incident was reported to the judicial authorities on Thursday, with spokesperson Sebastian Brux confirming: "All cells and passage doors have therefore been changed."
These efforts didn't come cheap. Not only did they need to buy new locks and keys, but it took 20 of the facility's staff members to install the new security setup, not to mention the cost of having to get the old keys destroyed.
Even though there has been no official update on the outlay, experts estimate that it would have cost the prison €50,000 (over £43,000) to replace the system.
Meanwhile, spokesperson Brux said that the costs could well be billed to the bungling trainee, adding: "The intern was banned from entering the house with immediate effect and the internship ended."
So not only did he likely lose his job, but his mistake could cost him BIG time - all because of a single WhatsApp message.
Unfortunately, he learned the hard way why you shouldn't act like Billy Big Boll***s in front of your mates.