Pasarse de la raya, de lanza, de corneta, de camote, de verga means to disrupt someone or something by going too far, trespassing some norms. The trespasser is referred to as pasado (de lanza, etc.) or just pasado. Finally, pasadez is the act of trespassing.
Ese güey es un pasado de verga => That dude is quite an asshole, beware!
¿No te parece que te pasaste de lanza al abrir mi e-mail? => Don't you think you went too far checking my e-mail account?
¡Qué pasadez de lanza de tu chava! => What an abusive behavior of your girlfriend!
These terms are as informal as effective conveying their message. Use them wisely.