And the cast gets eaten by the play

This meme worries me slightly . . .

sovay's Halloween party:

apotropaism dressed as the Governor of Alaska.
clarionj dressed as a zombie.
coffee_and_ink dressed as Barney the dinosaur.
dgr8bob dressed as Calista Flockhart.
dingbatfiction dressed as a ferret.
fetishpunk dressed as a first baseman for the Blue Jays.
fleurdelis28 dressed as Counselor Troi from "Star Trek".
godlyperspectiv dressed as a part-time webmaster.
greyselke dressed as Denise Richards riding a badger, though it looked more like the Lethargic Power Ranger
hans_the_bold dressed as your sister.
jaded_dreamer dressed as a hedgehog, and it suited them disturbingly well.
knowing_carrion dressed as a monopoly.
kraada dressed as a bottle of Agiloid.
lesser_celery dressed as an angel.
matociquala dressed as Mary-Kate Olsen with her very own conjoined Ashley.
nineweaving dressed as an external hard drive.
papersky dressed as your uncle.
pnh dressed as the spirit of their dead grandmother Heather, and it suited them disturbingly well.
poliphilo dressed as a sample ash.
rushthatspeaks dressed as your mother.
schreibergasse dressed as the President of Germany.
shirei_shibolim dressed as a plan, though it looked more like the equator.
strange_selkie dressed as a sleeve.
the_red_shoes dressed as the King of Libya, though it looked more like a interrim computer programmer.
thomasfreund dressed as Chester A. Arthur.
time_shark dressed as the love child of Jim Carrey and Janeane Garofalo.
upstart_crow didn't dress up, spoilsport.
weirdquark gets drunk, strips naked, and somehow emerges dressed as a 1980’s yuppie child.
yhlee dressed as the love child of Harrison Ford and Gwyneth Paltrow.
yuki_onna dressed as Queen Elizabeth.

Throw your own party at the Hallomeme!
Created with phpNonsense

Among other things, what's with people going as members of my family? Including the nonexistent ones?