His 10 posts look similar to official posters noting service changes. Apparently, the guerrilla etiquette marketing effort has begun.
"MTA poster parodying graphic designer Jay Shells wasted no time kicking off his much needed ‘Subway Etiquette‘ campaign. As promised, the artivist started installing the appropriately modified posters on Wednesday morning, beginning at the 8th Avenue L station. Despite its highly illegal nature, this is the type of vandalism that even the graffiti-hating public can back. And remember, if you see something, say something."