I’d say “So long and thanks for all the fish.”
I would be pretty pissed, but mostly because all these end-of-the-world idiots turned out to be right.
This happened to me durring the big Y2K scare:
Jan 1st 2000, beautiful day out,. The sun was shining. And then, all the sudden, the electricity goes out for no apparent reason. It only stayed out for like five seconds, but still, that was long enough to make me think: “Oh Shit!”
5:11 central means my husband won’t have gone to bed yet, and my son will be either in our bed or in his bassinet next to it, so I’ll be set.
And 6:11 EST means that if it takes long enough I’ll get up and feed the cats one last time (they might as well die happy) and if it doesn’t I’ll just think “Ugh, I’ve got to get up. Oh. Or not.”
I’ll be on a boat in the gulf of mexico… so I’m probably going to drown in some sort of a big tsunami… not a good way to go! I’d be really sad that I wasn’t able to hold my boyfriend or my sister or whatever one last time before being snuffed out of existence forever.
Honestly? I would breathe a sigh of relief, hug my dogs and say good-bye. As long as we all go together, I’m ready.
But can you imagine the lines at the Pearly Gates? I don’t think they’re equipped to handle a crowd of that size.
Can I arrange for some sort of pre-screening or something? Go ahead and punch my ticket for Hell now, and I won’t have to go out of my way. Maybe there’s a website.
On the bright side, they can’t get into your face and say “I told you so!”
Yes, I would gladly welcome our annihilation.
“Oh hell yes, there’s a non-zero chance shit will turn out like Shadowrun. I hope I get to be a dragon!” 
This.
Sometimes the innocent suffer along with the guilty.
Hasta mañana, Senora loca o mujer loca.
Yep. But my Dane would be suspicious, assuming I wanted him out from under the covers again.
I would mutter “Damned train” and go back to sleep.
I’m secretly hoping.
Now this made me laugh! (Sorry.) I can picture the two canines punching a time clock like Ralph Wolf and Sam Sheepdog.
Oh, I don’t think there will be that many there. The road to hell, on the other hand will be just…hell (only not as hot). May as well get used to it.
When I wake up on Dec. 22 (or 1/1/1 in the Mayan calendar), I will chortle once more: Those idiots. Do people actually believe this drivel or is it some kind of scam?
A side note - the Mayan calendar doesn’t really end on December 21; in fact, they have units of time as long as 63 million years (see table here), although not commonly used. For example:
So, December 21 is more like going from January to February than to a new year (as Hari Seldon put it).