It's become customary for each Doctor to have his catchphrase, and Smith's became geronimo after his very first appearance at the end of series four. There are plenty of dramatic moments when he cries out this simple phrase, but the most epic instance comes in the form of a text message. It's The Big Bang again, and the TARDIS is exploding in the sky, messing up time and causing all kinds of havoc across reality. Well, cue the epic soundtrack, because the Doctor's about to sacrifice himself in the name of the planet again. Smith, already in a bad way from his earlier battles, straps himself into his former prison and launches himself into the atmosphere, into the heart of the exploding TARDIS, knowing it will erase his very existence. Back on the ground, River Song gets a text. "It's from the Doctor," she says. "What does it say?" "Geronimo."