I like to leave un-commented lines of vulgar text in my code when it's time to call it a day but I'm still working on solving a problem.
Then the next day, when I try to compile, I get an error for "This fucking shit-ass function should be returning 64 instead of 128, but I'm a dumbass and write shit code" not being valid syntax.
Subsequently, we quantified the adherence of these two distinct sets of source code to coding standards, which we deploy as a proxy for source code quality
So basically, if there are curse words in your comments it probably means that the people calling the shots on the project care more about the code being functional and maintainable than policing political correctness of the comments.
I spontaneously curse at it, in 4 different (spoken) languages even and abundantly so at times, but I don't feel the need to actually write down the swear words.
Writting it down just doesn't feel the same as merelly just letting out those expletives that naturally arise during the making (and, especially, testing) of software.