"Rose clambered in after Iris, subconsciously manoeuvring to block the Doctor’s view of her plastic-clad buttocks. She stumbled over the steps, her mouth dropping open as she took in the interior of the magnificent transcendent time machine.
‘So it’s just a bus?’ she said.
‘Just a bus?’ spluttered Iris. ‘I’ll have you know this is a fully functioning Time And Relative Dimension In Space craft. Type – oh, I forget. But it’s one of the better ones.’
‘But it’s the same size on the inside!’
‘Oh yes. It’s the latest thing you know. Dimensional transcendence is so passé.’
‘But it looks just like a bus! Where’s the console? The roundels? That bit that goes up and down when it takes off?’
‘The control console is ingeniously disguised as the dashboard and gears of your standard London double-decker. The time rotor is integrated into the rear engine of the craft. And there’s a roundel over there.’ She waved vaguely left.
‘That’s a washing machine.’
‘It’s round.’ "
That is one of the greatest bits of a fanfic I've read. To read the rest just click on the extract.