The Trouble with Little Green Men

A wide gleeful grin was plastered across Jack's face as he stumbled into the TARDIS and waved his arms around widely to find something to support. "A gaggle of dancing beer bottles with top hats," he sang loudly "and twenty cans of ruuuuum…"
"I was watching him the whole time and I swear he couldn't have had more than four drinks," said Martha fretfully as she and the Doctor guided Jack to the couch. "I don't know how he could've possibly gotten more."
"How indeed," said the Doctor dryly. "Keep him there. I'll be right back."
Martha nodded uncertainly, nervous about being left alone with the drunken Jack. "No nonsense," she said in a confidence she didn't feel. "You got that?"
"Nonsense?" Jack repeated thickly, smiling dazzlingly. "No, no nonsense, Marsha. Nonsensical…would be impulverized…impossible…" he frowned. "Improblemental? Like a monkey!"
"Really" Martha said, muttering 'crazy'.
"Monkeys at the moon. I want to go to the moon with those monkeys, Marsha. Great…absolute…who would win at a fight? An astronaut or a caveman?"
"I…haven't the slightest idea." She cleared her throat. "Um, Doctor?" she called down the hall. "He's raving like a lunatic and you left me alone with him…"

Jack narrowed his eyes. "It's the little green men you've got to worry about, Marsha. A single one could take the TARDIS and alter all of history and there's no way to stop them once they've done that. They were following us."
"Really…" said Martha, nodding slowly, trying to make civil conversation. "Well I haven't seen any."
"You haven't seen them yet, but I know…they're out there just waiting…Think they got in? OI! GREEN MEN! Come out where we can see ya!" He lurched forward, nearly falling off the couch as he clumsily drew his pistol. "Think you can stowawowawowaway on the Doctor's TARDIS? Dare you challenge me, the single person in the universe who is unaffected by your trickery! Come out and face me, cowards!"
"Doctor…thank heavens," said Martha in obvious relief at seeing the Time Lord return. "Is there any way to help him?"
"No worries. I've dealt with this before."
"The little green men are here," said Jack insistently as the Doctor scanned him with the screwdriver. "And they're gonna be messin' stuff up if I don't…" he tried to get up, but the Doctor shoved him back down. "Gotta let me stop them. The whole of the universe is at stake!"
"It's just your imagination. When you wake up later, you won't remember a thing."
"But that's what they want you to think! The little green men are influencing you! They have mind control and I'm the only one immune to it. Grab him, Marsha!"
"35%...could be worse," said the Doctor outloud, tucking the screwdriver in his pocket and reaching for a packet of white powder, which he emptied into a glass of water.
"35%? He should be unconscious!"
"Jack's a strange one. You'd think something would hurt him, but he just keeps going."
"What's that?" Martha asked, watching him methodically stirring the contents of the glass.
"Antidote" he said calmly.
"But you're not supposed to…!"

"A LITTLE GREEN MAN!" Jack hollered, nearly deafening them both, pointing frantically down the hall. "I saw it pass by! Let me up and get it before it mind controls you both! There's a whole army of them…if there's one there's a bazillion!"
"Brilliant idea, Jack," said the Doctor. "You're right, absolutely right. If we don't capture those little green men overtaking my TARDIS, the whole world is doomed." He thrust the glass into Jack's hands. "We've got to stop them and just as soon as you're well again we'll be off…aaaauuurgh!" He moaned and crumpled to the floor, twitching violently.
Martha screamed.
Jack sat bolt upright. "Doctor!"
"Mind control…they're getting me…" said the Doctor in a hoarse voice. "You're…you're the only one who can stop it, Jack! Can't…resist…" he grimaced as he clutched his head with both hands. "Too…strong…can't…can't fight…back"
"Tell me what to do!"
"Antidote…will…protect you…"
Jack looked down at the glass in his hands. "You mean…there's an antidote against the little green men? You need it more than me!"
"Too…far…gone" managed the Doctor through clenched teeth. "Stop them…Jack…save…the…world…before…"
"Before what?"
"Too…laaaaaate…" he gasped then was completely still.
Martha was next to the Doctor in a flash and frantically listening for heartbeats. "Oh you've got to be kidding me. There's no little green men…there's…oh my gosh…Jack, he's…his hearts have stopped!"
"Mind control by the little green men! I'll save him!" Jack fumbled with the glass in his hands and drained the contents in a single gulp. "Those green men have no chance against ME! One or five billion hundred, I'll get them all," he boasted as he drew his pistol. "LITTLE GREEN MEN, YOU HAVE BEEN WARNED!"
"Well don't just sit there…DO SOMETHING!" Martha shot back, starting CPR. "If the Doctor dies, it's all your fault!"
"Sure thing, ma'am…er…Marth…Martha…" Jack shot up from the couch eagerly. "I'll get those little green men and they won't know…won't…know…" his voice took on a tone of uncertainty. "Little…green…" Jack took one unsteady step forward and slumped to the floor unconscious.
Martha's eyes widened as she looked from the Doctor to Jack. "This isn't happening…it can't be happening! There are no little green men! Oh…COME ON, Doctor! Don't die! Not now!" She bent down to resume attempting to revive the dead Time Lord when he sat up so suddenly that she fell back in astonishment.
"Jack'll be back to normal in a few hours," he said as if nothing had happened.
"You…you mean that was a trick?"
"Not exactly" he said. "I had to get him to drink that somehow. What did you think it was?"
"That was a trick"
"Well…yeah…if you want to get technical about it" he looked up at her and his expression lost all traces of glee. "Martha?"
"THAT WAS A TRICK?"
If looks could kill, Martha would've killed the Doctor ten times over.