One of the great things about living in the UK is learning their colorful (colourful) language. A particularly fun aspect is of course, swearing and the fine art of the British Insult.
Fuck and shit are used pretty commonly (obviously not in polite society :P) and you'll often hear it on tv after about 9 pm.
Mother effer and sonofabitch are almost never used, and when you do hear it, it's probably because they're making fun of Americans. Same with douchebag.
The C word is used a lot more here than in the states and I'm still coming to grips with that one. I'm not quite up to speed at when it's ok to use it affectionately about your mate, versus someone who cut you off on the motorway. If the person wants to communicate the same essence of the C word, but not as harsh, they'll use the disturbingly cute sounding "twat".
Then there's asshole. Another one used to usually make fun of an American. Unless you hear someone say arsehole, when you're probably talking to my Irish friend Pete.
I like the insult of calling someone a tit, but I have to admit I can't pull it off as it sounds much better with a Scottish accent.
Wank is a good insult. It's a nice alternative to calling someone a dick and I think America should adopt its use right away.
Bastard is pretty weak but your wit will be rewarded with admiration all around if you can spice it up with key adjectives describing your opponent ie "Saggy pants bastard"
Then we come to muppet. Yeah, muppet. I'm not sure when it's appropriate to call someone a muppet but I think it's like the daytime television appropriate version of the C word, which is pretty harsh for something that's usually associated with Sesame Street.
On the flip side, I have been slowly attempting to inject "What the shit" and "fucktard" into the British culture. So far nae luck, but I have a feeling I'll hear them on Big Brother next season and I shall be vindicated.