For example: If u are in classroom and u stand up from ur chair to go to the toilet and when u are at the door ur teacher ask u: "Chi ti ha dato il permesso di uscire?" = "Who gave u the permission to go out/to leave the class?". It means that u are not polite, u wanted to go out without ask to ur teacher the permission. :) Ask me again if u need again about ur question.

It's a rhetorical question. Nobody gave him/her the permission to go out (uscire) so "the boss" can use this expression to remark that no permission was given. Can be used in a friendly way or can be quite harsh.