There really is nothing like a good swear.
Most often, I find inanimate objects are the target. My crashtastic computer, that street light that changed up ahead, that table who's leg I just kicked. All of these are perfect moments to expand the old profanity repertoire.
These days, swear words like 'fuck' or 'shit' are too commonplace though. They fail to shock anyone anymore. Hell, you can hear them on regular TV after 9:00.
I've become a big proponent of Al Swearengen. If you haven't seen it - Deadwood is easily one of the best shows that HBO has put out the last couple of years. It also has possibly the most swearing ever heard on TV. Al's favorite is 'c#$!sucker'. I'm a firm believer that 'c#$!sucker' should be brought back into more public usage. Try using that next time you were going to say 'fuck' and I guarantee more people will pay attention to you.
Until the children of today are using 'c#$!sucker' around the dinner table, my crusade will not be done!