The building formerly known as Oz's Meat.
A Graffiti Canvas prim is provided; you create, upload and apply your own texture. Then simply situate your prim on the building. There are guidelines (read the notecard), and the objects will be cleared as the parcel fills or at Oz's whim.
Painting the town.
Black Market - Community Graffiti, Sistiana (134, 242, 45)
Elka's Spray Paint, boing fromage, Miramare (168, 167, 27) In the jewels/accessories/gadgets vendor - there is a tiny version too.