Error messages

I'm at work right now. In this application I'm writing, the error messages are:

- You're doing it WRONG (user data entry failure)
- NO U (for permission denied / caught attempt to fuck with me)
- DO NOT WANT (for internal unexpected errors)
- Fail (other errors)

I don't use errors, I have more important things to worry about. I just add in documentation that, yes, run time errors do occur and that user shouldn't do again what he did to cause it.