The act of advertising by leaving printed promotional materials where someone will have remove it and/or throw it away to go about their daily business. Fliers on door handles, fliers on car windshields, "sample" newspapers in the driveway. These items often end up in the parking lot, street, etc. as people typically just throw them somewhere to get them out of the way.
Neighbor 1: "Watcha doing?"
Neighbor 2: "Fixing my snow blower. Blades are jammed." *grunts*
Neighbor 1: "From what?"
Neighbor 2: (pulls out a mangled wad of paper) "That stupid ad-covered newspaper thingy."
Neighbor 1: "Salty. You get the daily paper?."
Neighbor 2: "No. It's just a bunch of ads they give out...try and get you to subscribe. They throw them all over the neighborhood."
Neighbor 1: "What dicks."
Neighbor 2: "Yeah...I hate the Plain Dealer and their trashvertising. It's gonna cost me $50 to have this thing fixed."
Creating awareness of a product or service through items usually found in public trash cans.
(two people are walking down a street when one notices an Arby's cup sitting in a trash can)
person 1: Hey, you wanna go to Arby's for lunch?
person 2: There's an Arby's around here?
person 1: There must be. I just saw their trashvertising.