This might sound like something from The Inbetweeners, but genuinely it's not.
A Reddit user spotted what at first glance appears to be a pretty rude sign on an Iarnród Éireann train... Something about a cock and a box?!
We can only imagine the shocked looks on sweet American ladies' faces when they're travelling down from Dublin to Galway and look out at the train only to see this...
Don't worry - a cock box is actually a real thing.
Another Reddit user replied: "Iarnród Éireann engineer here. The cock isolation valve is used to control the air pressure between the forward pump gasket and the 24volt generator array.
"You'll need a hex-b key tool to access the cock box but it has a perspex window where you can see the current PSI and voltage without having to open it."
We've never noticed this before, but just know we'll never be able to take a train journey again without pointing it out. Immature? Yes. Still funny? Yup.