Sledge and Dori go out of their way to remove anything police related from his apartment, but they leave up a giant police issue silhouette target on the wall and even glance at it as they scan the room.
When the scumbag enters his eyes go around the apartment and even he notices the target.
The title is from the 1949 song "If I had a Hammer (The Hammer Song)" written by Pete Seeger and Lee Hays for The Weavaer and was a big 1960's hit for Peter, Paul and Mary.