That was a “bad idea” – according to a water company which fished them out of its system before they caused a major blockage.
Severn Trent said it found the pair of size 14 pants with the name “Eileen” on the label at its Hayden Sewage Treatment Works in Cheltenham.
The firm has released a photograph of the unexpected find to highlight one of the issues its says it faces on a regular basis.
For pants are not the only unusual item to be flushed down a toilet – previous discoveries have included tennis balls and even a motorbike broken down into parts.
Paul Tingle, from Severn Trent, said: “We find all sorts of things in our sewers and in treatment works that simply shouldn’t be there because they could cause blockages.
“I don’t think I need to tell anyone that putting your pants down the toilet is a bad idea, and “Eileen” is very lucky that she didn’t cause the sewer pipe to flood both her home and her neighbours.
“There’s a reason why we ask everyone to only put three Ps down the toilet – pee, poo and paper. Certainly not pants!
“Even if they make it through our sewer pipes, which are often no more than six inches in diameter, the pants could clog up our treatment works, so we want everyone to think long and hard about what they put down the toilet.
“But never pants, that’s just odd!”