While in the 2nd dream (set after the junkyard), there is a poster in front of Chloe.
Look at the poster.
Move the poster.
Graffiti the area under the poster and Chloe will ask where her pen went.
Look at the wine bottle.
Take pen from wine bottle.
Graffiti the area under the poster again and choose your graffiti to get this trophy to pop!
NOTE: The order I wrote is important. Each new Look on an object would move the dream sequence forward, and the pen would only appear if you look at the wine bottle after attempting Graffiti at the area under poster. If you Look at the third object (mannequin head) before you graffiti, you will end the dream sequence and miss your tag.
Thanks to TheLahaarl for the mannequin head note that made me double check and give more detail!