Old wives tale (I’ll translate as best I can):
Once upon a time, on a ferry, one of the windows broke and the people on board had to find something to stop the sea water pouring in…......eventually this married man grabs his wife, sticks her bum in the hole to block it. The wife commented “the bum can handle it” – and as a result, ladies bums are always cold…..
The above is from an unofficial, unconfirmed source, no responsibility taken for it’s accuracy