JDKJ said:
The Americans have their equivalent: yanking your chain. It goes back to the days of gravity flush toilets that had a huge tank of water above the user's head and which were flushed by pulling on a chain. They flushed rather violently and were know to splash your ass with water if you were still seating on them. As a school prank, it was common to yank the chain while someone was still sitting on them, hence the expression: yanking your chain.
Now if only I had some actually useful information in my head, I'd be "sitting in high cotton" (a polite form of the traditional "shitting in high cotton" used to denote a beneficial situation).
Wow, I did not know that! We also use that expression, but it's not as widely used as some others. Also, we still have those toilets in some places over here, especially older buildings. Yeah, we're still stuck in the middle ages