Dont post PDFs.. unique codes..
(well, not really, see below)
This will print out an entire colored page. If you wanna save ink, make sure to set your ink setting on your printer.
But more than that, they are obviously a part of the background image, as suggested by the fact they are scaled and dithered equally with the rest of the page, excepting "This coupon is for XYZ" and the supposed serial number. The catch is that bar codes cannot be dithered: gray scales and smeared bars invalidate them (or at best, give incorrect values).
My two serial numbers also seem to have zero relationship to each other, and given the fact the bar codes are a sham, this probably means the serial numbers are randomly generated. The moral of this story: if you know how to capture your print jobs, and you are paranoid, just edit the image with new info. If you are not paranoid, just xerox as many as you want.
mcdonalds registers have a 'coupon' button, they just click that and apply the coupon you brought over. i found out on a $1 off coupon, i just printed the same coupon 4 times on one page and it worked all the time.
so, in theory someone can just get the coupon and attach it to the wiki, and you're good to go