"What about space pirates, Doctor?" Rose asks.
"What?" He shoots her an incredulous look.
"Um. . . y'know." A brief hesitation. "Space pirates."
"Space pirates?" He's still giving her that look, vaguely suspicious as though he thinks she might be making fun of him
"Yeah. With, like, spaceships. . . n' stuff." She shrugs, almost apologetically.
"Space. . . pirates?" Suddenly he's not looking at her but, index fingers steepled above clasping hands and resting on his lips, at some invisible thing drifting far outside of Rose's vision.
"Well, y'know, I was just thinking that—" she begins, but the Doctor interrupts.
"Space pirates. Space pirates. Space. Pirates." He's doing that thing that exasperates Rose to no end, the things where he chews on his words, with his face scrunched around the eyes in consternation. Suddenly, he perks up. "Space pirates! Why, Rose, you wonderful. . . you—" He breaks off with that infectious laugh of his and she's smiling now, too. "C'mon, Rose Tyler," he grins, dashing to the TARDIS. "We've got some space pirates to catch."
As dichotomously ridiculous and dangerous sounding that statement is, she can't help but laugh and run after him.