This graffiti is in the hospital. The location is always the same but not the way how to get this graffiti. There are 2 small different ways depends on your decision in a previous episode.
First, please get graffiti numbers 6 and 7 before you miss them in the hospital.
After you get both graffiti go from the starting point straight forward to Mikey's / Drew's dad and after the short dialog enter the hospital room behind. Due to the decision in an earlier episode, you have either Mikey or Drew in the hospital bedMikey:
Listen all automatically dialogs (cutscene) then go to Mikey and sigh his cast.Drew:
Talk with Drew then duel with him over his pudding (does matter if you win or not) and after the short cutscene sigh his cast.
For a visual guide (Mikey) open the spoiler, inside you find my video with all 10 graffiti locations.