What's the best way to increase the jolliness of Christmas Eve by about a hundred percent? I don't know, but I DO know a surefire way to decrease the jolliness level. Here's what you shouldn't do.
You shouldn't try to vacuum the filthy and mostly unused upstairs bedroom in which there are supposed to be people sleeping tonight without first turning off all the space heaters in the house because it turns out that that bedroom is on the same circuit as Cubby's bedroom and the MiL's bathroom, neither of which connect with said bedroom and so would not logically be on the same circuit, but both of which have space heaters and are thus overloading that circuit already without the additional electrical strain of a vacuum.
If you do decide to do such a foolish thing, you will then spend a (very jolly!) half hour trying to figure out which fuse box that circuit connects to--because OF COURSE there are two in our ridiculous electrical system--and then trying to figure out which of the glass fuses was the one that blew, and THEN going to the hardware store because OF COURSE we don't have any replacement fuses for that particular number of amps.
So don't do that. Stick with booze. I think that would be a much safer bet for jolliness.
Merry Christmas Eve, poppets! May your day be merry and bright (because you aren't a dumbass like me).