I also have problem to translate it: For whom who do not know it there is also literar word for it ... buttocks. (there is "co to nevědí" written but it means (and is correct/literar) "kdo to nevědí" I think it originally was very derogatory and vulgar but vast usage moved it to place somewhere between vulgar and common word. In Bohemian region would be used vulgar word for penis instead of it. But it is very vulgar word. I think cyp is now less vulgar and rude then its western equivalent. Maybe somebody from Ostrava or Moravia will explain how much rude and vulgar is this word there. For ppl from Bohemia it is just "Moravian" word.