A second phone used for important call only. Businessmen who get a lot of phone calls will often carry a second cell phone and only give it to certain people. Ari Gold carries a bat phone with him.
Now I have to answer the fucking batphone when it rings three fucking times and its fucking Vince.
Noun- a man or woman you can call on short notice for a hookup, similar to a booty call. The word derives from the phone Commissioner Gordon could use to contact Batman any time of the day or night.
"I'm pretty hard up tonight. I better call the batphone."