What does it mean when a dead person comes in your dreams and is rude to you?

Whether or not this dream is significant depends on the relationship between the dreamer and the deceased. If the deceased is a parent or close family member, the dream suggests unresolved issues in the relationship, particularly if the death is recent. The dream could be part of the normal grieving process, as the dreamer's subconscious struggles with anger at being abandoned by the deceased. ("How rude of him/her to go off and leave without saying goodbye!") If the deceased was not dear to the dreamer, then he/she probably represents something else in the dreamer's life: a teacher might represent education or authority, etc.