OK, your guess is as good as mine.
I've been searching the interwebs, but I can't find anything that explains what this day means. I've found several sites that mention that it is indeed National Cheese Sacrifice Day, but none that go into detail as to what it is. When Wikipedia doesn't have something, you know it's odd. I guess we are left to speculate.
Does it mean that we buy some cheese and sacrfice it somehow, or does it mean we aren't allowed to eat cheese today, as a sacrifice?
Wikipedia does have a long page on cheese, so knock yourselves out. And here's out cheese category to browse.
Update: As a reader pointed out in the comments, it's actually Cheese Sacrifice Purchase Day. I've changed the headline but not the URL.
New York Times Magazine's food issue
Chicken McNuggets frolic at New York City pet store
Eat your broccoli orbs! 
Reader Comments (Page 1 of 1)
7-29-2007 @ 2:17PM
edpv2.0 said...
Apparently, it's actually national cheese sacrifice *purchase* day. Which at least a couple (http://gogogastronauts.blogspot.com/2007/05/honest-to-goodness-meal.html, http://www.all-yours.net/c/gallery/2507.html) of people think means you purchase cheese to sacrifice to a mousetrap. Because that makes total sense.
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7-29-2007 @ 2:23PM
AC said...
Apparently, it's actually National Cheese Sacrifice *Purchase* Day, which at least a couple (http://www.all-yours.net/c/gallery/2507.html , http://gogogastronauts.blogspot.com/2007/05/honest-to-goodness-meal.html) of people think means you purchase cheese to sacrifice to a mousetrap. Because that akes total sense.
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7-29-2007 @ 2:31PM
Julie said...
This was a new one to me and you are right, it is very difficult to find out the origins of this strange holiday. But I actually found 2 greeting cards specifically for; "National Cheeses Sacrifice Purchase Day" here is the link: http://www.all-yours.net/c/gallery/cheesesacrifice11.html
I'll keep looking,
tfjules
http://www.noshtalgia.blogspot.com
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8-01-2007 @ 7:05PM
anthonyturducken said...
read about the night of sacrificial cheese!!!
http://gogogastronauts.blogspot.com/2007/08/cheese-man-melting-of-star-bellied.html
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