‘Bog’ comes from the Gaelic, and means ‘soft’. From soft, it’s a small step in your wellies to wet, marshy ground. So a bog was a marsh. Another small step, but I would advise wearing waders for this one, and we land in a bog – or cesspit. Add to that the slang use of the word ‘bog’ meaning to defecate and the smallest step, to the toilet, is no surprise. The toilet, the can, the loo, the bog. And what do you use in a bog? That’s right – bog roll. Toilet paper.
Bog is also a verb. Your car can get bogged down in the mud, and you can get bogged down in work. You can bog off. Or tell someone else to bog off. But it wouldn’t be a polite thing to do. In fact, if you were to tell someone to bog off, it would show that you have bog all idea of etiquette. And bog all chance of that person sending you a Christmas card.
Lastly, a mystery. A reasonably recent use of the word ‘bog’ is in ‘bog standard’. Something that is ‘bog standard’ is completely ordinary, unexceptional. One possible explanation is that it actually started out as ‘box standard’, meaning the same thing – perfectly ordinary.
As perfectly ordinary as a bog roll, in fact.
Try singing along with the Irish song ‘The Rattlin’ Bog’ – link in the first comment. You won’t need wellies but it isn’t easy!