VENGEANCE IS MINE! *laughs crazily*
No, I’m just kidding.
I have no explanation for this, except that Jack Harkness is the epitome of inappropriateness.
Martha sat down heavily on the couch by the TARDIS console, and the living ship made a small, gentle, comforting sound. Martha sighed. She was on the very verge of falling asleep and she welcomed that, especially the relaxed lethargy.
Suddenly, her peaceful time was broken into by a bloodcurdling cacophony of screams, cursing, and wild laughter. Martha sat bolt upright as Jack appeared with the Doctor hot on his heels, laughing madly and brandishing a bar of soap. Jack saw Martha and dived behind the chair. “Save me, Martha! He’s gone crazy!” The Doctor advanced, a manic light in his eye, tossing the soap from hand to hand. Martha rolled her eyes. Boys and their games.
“I’m going to wash your mouth out, Jack!” the Doctor said ominously, but Martha saw the mischievous twinkle in his eye and relaxed.
“Go ahead and play, kids,” she said, closing her eyes again. “Just remember, Doctor, humans are fragile. Don’t go breaking them by accident.”
Jack, who was breathing hard despite his apparent immortality and being in perfect shape, gave an unmanly squawk and made a dash for it, but the Doctor was too quick for him. “I told you! First day. No flirting, no dirty talk, and no un-called-for snogging! Especially not me!”
The sounds of the scuffle died away into the distance as Martha closed her eyes in a well-earned nap.