"Contact, wait out" is a term military personel use over the radio to report enemy sightings/attacks. "Contact" means that the enemy has been identified or that you have already been attacked. "wait" means that you have no time to explain the situation right now. "out" means that you are about to end transmission and will call back later.
Lieutenant: Holy shit, call it in!
Radio operator: This is Mike November 4, contact wait out!
A term used in the military, for storming a house using violent force. It doesn't nessicerily mean shooting or throwing grenades before entering a room, but the soldiers will be highly alert and ready to do so.
The opposite is a "soft knock" which means knocking on the door and "asking" calmly to come in.