Let's say you have a young student, who has a pretty significant hearing loss in addition to other special needs. She is just learning to talk and use language, which she unfortunately was deprived of for the first six years of her life.
When she needs to go to the bathroom, instead of using the appropriate terms for bathroom she may say, "Piss." or "Poop."
What do you do?
Well, I can tell you from my training and experience, you should not discipline the child or tell her not to use those terms. Instead you can say or sign, "Oh, you need to use the restroom? Okay. Let's go to the restroom." And you keep doing this over and over again until she starts to model your language. Ideally, that is how it should be done.
In my opinion, it is not a good idea to keep a child who is language and/or speech delayed from communicating. You have to try to put yourself in the child's position. This girl, who did not have any type of language for a huge portion of her young life, may not understand why saying "piss" or "poop" is not appropriate to use while in school. It would probably change things if you learned that these were the only words she used in the first six years of her life to let others know that she needs to use the bathroom. When a child is just learning to speak, sign, or use language, the last thing we need to do is punish him or her for trying to communicate.
Sometimes it is worthwhile to think before you are quick to discipline or dismiss a child for saying inappropriate things. Depending on how well they can comprehend language, sometimes it just takes a simple explanation as to why what they are doing is inappropriate.
But, if the student or child knows and fully understands why what they are doing is wrong or hurtful, then by all means discipline them!