In the hospital you see vending machine. first get Graffiti 7
*** Spoiler - click to reveal ***In hospital after the dialog when you arrive her you go right than you see two people that you know after the are gone you walk to the door you will she left a poster with nurse on it with text "Wash Your Hands!" that will be Graffiti 7
before you can unlock this one. After you did get graffiti 7 go to the vending machine again and get di caddy bar form the machine after that you can send graffiti 6 on the vending machine