A giant Meteor is 15 seconds away from earth....

[God's Clown]

"Is it here yet? No? What the fu-"

 

[TheTurtleMan]

"Geez, it's a good thing I single handedly saved everyone on Earth and that they will now remember my heroic act by worshipping me as if I was a god."

 

[cornmancer]

Screw that, I'm going to kill myself. Get into hell before the line starts

Actually I'd probably just say
"Well fuck"
"Oh shit"
"Fuck it"
Something like that.

edit: Wait no I've got it
"Ob la di, ob la da life goes on la la la la..." or Always Look On The Bright Side Of Life.

 

[Teh Ty]

"Wooooow... That's a big rock. Welp, that's all, folks."

 

[RustyRampage]

Option #3:
Oh dear.....................*opens tiny umbrella and holds above head like wiley coyote*

Oh man, ninja'd.

All right then, how about: "I guess chicken little was right."

 

[gamefreakbsp]

Adios Mother Fuckers!!!!!

 

[Teh Ty]

Oh, wow, Thas' a big rock.
Welp, time for a nap.

 

[Instant K4rma]

"Giant flaming rock? Coming to crush my planet?!"

*Charge towards the meteor*

"Come get some!"

 

[Clockwork Ninja]

"404: Planet not Found"

 

[lukenhiumur]

"DAMN YOU BRUCE WILLIS!!"

"Show me your Moves!"

 

[ViolentlyHappy91]

"You know, i'd always thought about this kind of situation, but no it's happening, I can't think of a single cool thing to do or witty thing to say...fuck!"
You know that you'd say the same thing.

 

[icarusfountain]

"It's not fair! I had time now!"
"Oh hey, look, it hit the moon. Overzealous pricks."
"Don't Panic" (alternatively, "at least I've got my towel")

 

[Guitar Gamer]

Option #3:
Oh dear.....................*opens tiny umbrella and holds above head like wiley coyote*

Oh man, ninja'd.

All right then, how about: "I guess chicken little was right."

WHY DIDN'T WE LISTEN TO CHICKEN LITTLE?!!?!?!
WHYYYYYYYYYYYYYYYYYYYYYYYYY?!?!?!

 

[Brad Shepard]

Have fun with the bomb!

No, im kidding, I would tell someone special I love them.

 

[Nouw]

"I'LL ALL HAUNT YOU FOREVER AND KILL YOU IN YOUR SLEEP!"

I'd scream that

 

[Extra-Ordinary]

If I don't have time to tell that special someone I love them, then I'd charge toward it yelling "WHAT YOU GOT!?!? WHAT YOU GOT!?!?!?"

 

[RicoADF]

I'd say 'I love you' to a certain someone.

Yeah it's corny, but it's something I feel needs to be said. No pithy one liners, just total honesty in the last few seconds of your life.

Same, with a final kiss

 

[Infernai]

"...The Names Plissken, and on the off chance i survive this Comet: Bob, your fucking dead for stealing the last seat on that Pod!"

Or, the good old Fashioned

"Someday we'll remember this and laugh, and laugh, and laugh OHHH BOY! Well, you may as well come on back"

 

[GlobalJim]

"Run son, RUUN!"