…well, sort of.
A blogger named Geek Graffiti created this site where you can download a file to print a sheet of cold sores on adhesive paper. You then cut them out and stick ’em on any ad you like. This is a little east-coast centric because we don’t have any subways in Portland, but I am sure that it would easily work on ads on MAX trains or bus shelters. It always makes me giggle when a tagger has dared to climb up a bilboard and spray-paint semen on the face of model for make-up or some other such shennanigans. This is the same thing, only a lot safer! Visit the site and get to work people!