| Though not officially recognized by the US Army, this is a semi-guarantee that anything an individual says immediately afterwards will /not/ be held against them. It is usually seen in this format.
"Sergeant, request permission to speak freely?" "Granted." "Sergeant, I think you're a lying sack of shit, and if you had any integrity, you'd let yourself be drummed out of the service."
The request is usually made when an individual of lower rank wishes to say something to an individual of higher rank which is either:
1. Profane. 2. A negative reflection on the individual in question. 3. A negative reflection on the shortcomings of a higher-ranking individual 4. A comment or criticism on orders, or a political opinion about current leadership. Usually Democratic or liberal opinion, it is almost always okay to express conservative views.
However, contrary to common misconception, this guarantee really only relies on how much the higher ranking member values the good will of his fellows. Such a higher ranking member has a perfect legal right to prosecute, and some have done so. However, those who do such things tend to find other people making their lives very difficult.
A note: this is drawn from my personal experience as a SGT in the Army. Action movies and other services may vary from this account. | 
