The QR Code in Dr. Zed's Clinic in Borderlands 2 is located on the door of one of the Corpse refrigerators, on the inner side of the door (see picture)
It says:
"Thank you so much for playing our game, now I'm rich with love AND money! !!Nick Wilson!! Ditto!!"
Nicholas (Nick) Wilson is one of the developers from Gearbox Software.
