First of all, it’s important to note that swearing in Japanese is very different from swearing in English, in many ways. The biggest difference is that there are almost no exclamatory expletives (in English, for example, ‘fuck!’) that you can’t say in polite company. It’s not rare to hear くそ！ (kuso, literally ‘shit’) on TV, or even ruder forms such くそばば (kusobaba, shit-hag). There aren’t really equivalents for the massive range of undirected swearing that people from Britain, for example, are capable of. (We’re thinking of the opening scene from Four Weddings and a Funeral here. If anyone knows what the Japanese subtitles were for this scene, leave us a comment!)
Other words quite commonly heard on TV include 死ね！ (shine, die), which is one of the worst things you can say to someone if serious, but which is often heard in a jokey context . Another is the well-known ばか (baka, idiot), which some talk show hosts such as Shimada Shinsuke use regularly on their guests. Most sex-related words such as おっぱい (oppai, boobs) are completely fine.
However, what’s perhaps more interesting are the words you don’t hear on TV. The Internet being the wonderful place it is, here is a list of words you can’t say on Japanese TV. Note that almost all of them are derogatory terms for a group of people, whether racist, sexist, classist, or whatever. And this is perhaps the most interesting part of Japanese swearing – there are virtually no words that cause offense just by being heard, even if you weren’t the target of the word. This is very different from English, where many words are forbidden even if they’re not directed at anyone in particular. The words on this list are offensive to a specific named group of people, so they are banned.
In practice, there are a few other words that are beeped out from 90% of TV shows, based on the time the program is aired. For example, crude words for the male and female sexual organs, usually (but not always) have at least their middle character bleeped, although everyone can tell what was said. The male and female equivalent of ‘slut’, respectively (add やり, meaning ‘to do’, to the start of the names of the sexual organs) also come up every so often, but you probably won’t hear more than やり on anything except late night TV.