Ten high school friends, upon graduation, decided to get tattoos of puzzle pieces that fit into each other:
After graduating high school, myself and 9 of my best friends got puzzle pieces on the side of our ribcages to represent our commitment throughout middle school and high school. Most of us had been friends since 6th grade, some before. We all got something inside our puzzle piece to make ours unique. All the pieces fit together, and we had a blast getting them.
http://fyeahtattoos.com/post/6640636396/after-graduating-high-school-myself-and-9-of-my
Seems like there are several pieces of the puzzle missing.