Underneath, Doctor Who, River Song/TARDIS
If you open the floor in the TARDIS control room you can climb down and into the insides of the TARDIS. River does this sometimes, when the old girl is grumpy. It's always warm in there, air heated from the life of the TARDIS.
River knows just what to do to make the TARDIS work again when she's been feeling cranky. You have to climb down there, underneath, and let the TARDIS envelope you in herself. It's like an out of body experience to River, like sex. The Doctor thinks she doesn't know, but she does. The TARDIS is sentient.