Rose Tyler circled the console of the TARDIS, skimming the many controls while being very careful not to push, pull, or otherwise disturb them. She smiled at the jelly baby shaped buttons, veered away from the ominous looking black switches, and ended up next to a large-ish red button. It intrigued her, the only labeled button on the board.
"Doctor, what's this button for?" she asked, poking him with her foot.
The Doctor was sprawled underneath the console, tinkering with something that, according to him, 'could be more sonic'. "What does what button do?" he asked without looking. "Is it an innocuous little white button? Don't push the innocuous little white button!"
Rose glanced around nervously for the white button of apparent doom. "No... This red one here."
The Doctor shoved himself out from under the console and came up to stand beside her. "Oh, that one," he exclaimed in recognition. "The TARDIS grew it the last time I redecorated. Old girl's still got some tricks up her sleeve." He patted the machine fondly.
Rose gave him a look. "Grew it? It just grew a new button?" The Doctor shrugged. Rose rolled her eyes at him and bent to read the label on the button. "'This red button doesn't do anything - press it and see!'" She looked back up at the Doctor, who shrugged again. Rose reached out, then paused. "Should I press it?"
The Doctor raised his eyebrows at her. "I don't know, should you?"
Rose's hand hovered over the button. "What happens if I push it?" He didn't answer, merely grinned at her like a loony bird. Rose sighed. Okay, he wouldn't even let me think about pushing it if something really bad was going to happen, she reasoned to herself.
Rose pressed the red button.
Nothing happened.
She smiled at the Doctor in relief. "Does exactly what it says on the tin," she said brightly, pushing the button twice more for emphasis.
A 'ding!' from one of the nearby monitors made her jump. The Doctor leaned over to read the message on the screen. "'The definition of insanity is doing the same thing over and over again and expecting different results,'" he read aloud. "Sassy thing in her old age, isn't she?" he commented to Rose, slapping the TARDIS' console.
Rose just laughed, and after a second the Doctor joined her. After a minute, Rose recovered enough to ask, "Does it do anything else?"
The Doctor's laughter tapered off into giggles and he answered, "If you press it 42 times, you get ice cream."
"Really?" she questioned with a disbelieving smirk.
"Really," he confirmed.
"What happens after that?" she asked curiously.
"Don't know," he said, going back underneath the console to his work. "After that, I was too busy eating ice cream."