Stencil Art is one of the side missions in the game, where you are tasked with spraypainting an image onto the wall. You get your first taste of this at the very beginning of the game, where you end up doing a little work over a billboard with your brother’s picture on it. They are shown on the map as spray can icons, and offer a choice between two pictures, one for Good Karma and one for Evil Karma.
In order to do these side missions, you will be required to hold the Dual Shock 4 sideways as shown in-game, then shake it as if it were a real can of spray paint. Each mural will be done in stages, with you holding down R2 while moving the controller around to fill in the stencil. The game will automatically move on to the next stencil once the previous one has been filled.