What is that feeling when you're writing a dialogue and want to swear but can't because it's for school?

I'm currently working on my 4th year creative writing dissertation and I'm stuck on this scene and every word that would naturally come out of the characters mouths is a swear word and I can't use that. My dissertation is supposed to be PG-13 and I know using that many swear words in a dialogue would not be allowed. This makes me wonder, how do writers write realistic dialogues and deal with the constraints of not being allowed to swear? I know that some people don't swear often, but in some situations it's inevitable. I just want to know how others have dealt with this problem.