Advertising of dubious or unintentionally hilarious quality seen in print, on TV, or anywhere around you.
Rule #1:
There's no shortage of bad design out there. Refrain from posting run-of-the-mill classifieds or poorly designed supermarket spreads UNLESS they are really god-awful, eye-burningly ugly or feature some funny copy/text.
Rule #2:
Real ads only, please. No spec ads, or mock-ups done for your Advertising 101 class.
Rule #3:
Ads so BAD that they're GOOD are more than welcome!