For years, I've used made up stuff to curse, but not because the words are 'dirty'. I decided that I wanted to save the real stuff for when things were REALLY bad, because if I swore casually, then nobody would notice when I really meant it. But now, each curse is like a verbal shaped charge.
Imagine Mr. Rogers swearing, and you get the idea. You'd sit up and take notice. Well, if he was still alive. If he swore now, I'd probably run away, gibbering like an idiot, because talking corpses are scary.
Lately, I've used 'frack' a lot, care of Battlestar Galactica. It's very flexible.
Other times, I make up elaborate curses that'd look extremely ghey in type, but work surprisingly well when spoken. Ok, and the unique swearing from Spongebob Squarepants is good to use around my kids.
One side benefit, I'm less likely to make an involuntary exclamation that could get me in hot water with Human Resources. It's not my primary motivation, but it's a useful side effect.
