I'm not sure if Jordan and Bryan Silverman, founders of Star Toilet paper came up with this idea after a bad flashback to those poor starving college days when household necessities always seemed to be further down on the grocery-list than useful things like beer, or what. You remember the paper or plastic days, right? The brothers have founded a company that puts coupons on toilet paper, and advertisers can buy themselves some soy-bean-based ink printed rolls, only $99 for 20,000 rolls. That's only half a cent per ad! What a deal! Avis will love this, I can't wait to tell DDB.
If you want to get really meta, you can wipe your butt with a twitter feed full of ads instead. Say, Kim Kardashians.