My gut feeling: when you start to submit swear words in your code, it indicates that you "breathe" the code and know it in and out.

The other extreme: if you have no idea what you are doing, you might try to mimic "corp speak" in your code to hide the fact that you actually have no clue.

In other words: it needs some confidence in your ability to assess some aspect of the code in order to use swear words.