You'll be horrified at what you're leaving behind for everyone to see...
There's a very good reason why passengers should never use the on board toilet while a train is waiting in a station.
And if you don't know, then you definitely need to read on because the new TV series Paddington 24/7 has exposed the grim reality beneath our behinds.
As a general rule, people travelling on trains are warned not to flush the on board toilet while it's not moving.
That's because most trains don't have sewage tanks, meaning anything in the toilet is dumped straight onto the tracks.
So as you can imagine, if the train is stationary, it can cause huge problems.
Human waste is deposited onto the tracks at Paddington station on a daily basis, causing it to pile up and create a rather disgusting mess.
Cleaning crews are in place to deal with the resulting sewage, but each member of staff must have had injections to protect themselves against infections, including hepatitis, before they can take the job.
Alex Kincaid, supervisor at Paddington station, works through the night to ensure the tracks are cleaned for the next day.
He said: "When you say to people, 'don't flush the toilet in the station', they think you're winding them up."
Gruesome footage shows urine, excrement and vomit pooling on the tracks as the cleaning crews pull up canvas mats in a bid to remove it all.
Alex added: "At the minute, a lot of the stock that the train operating companies have got, they don't actually have tanks.
"So when the train's driving down and you flush it, this is where it ends up."
Mats are put in place to protect the wooden sleepers and rails from toilet waste and other liquids.
They must be swapped out every three months as 40 million people travel on trains through Paddington every year.
Alex warns that without the mats, oils and other liquids would seep into the sleepers and grease the metal tracks - even leading to something as serious as train derailment.
So now you know, don't flush if your train is in a station.
Paddington Station 24/7 is broadcast on Channel 5.
