I personally don't use cuss words for variables in programs unless I'm making an application intended for adult use only and the variable name makes sense.
I do, however, sometimes curse in comments when I'm particularly frustrated by an API that I've only just started to realize is awful but have already written a large chunk of my code for and am too lazy to replace it. That doesn't happen as often as it used to, but it does still sometimes happen.
When I first created my Teamspeak 3 Query parser, I cursed all over for how stupid the protocol was. I had to do some incredibly goofy stuff.
Also whenever I made a play Minecraft Server, I had about a curse word in every packet parsed that contained a string because string size wasn't at the beginning of the packet which is absolutely stupid. In one packet, you have to have 4 or 5 different reads on the same packet just to completely parse it. In an asynchronous environment, this is very, very painful.
@Lumpkin - Probably best to lose that attitude. Some humour just doesn't work without swearing and some circumstances just need a swear word, you know, like when you hit your thumb with a hammer or stand on a nail a loud, sharp curse is definitely appropriate!
@fred: what compiler do you use? because idk about msvc++, but gcc can have some weird errors that warrant me saying things like <depression>F***</depression> and damn it gnu... give me real errors and not techinal f***ing jargon. one such occasion is when i have conflicting 32-64 bit libraries or i forget to specify bool as the data type