Thought I'd drop my prank as well. In highschool early 2011-2013ish QR codes were just becoming a thing. We had a mild vendetta against the year book committee due to the pricing of the yearbooks and their cliquey group.

We copied their "Reserve a year book early poster and save". Then used photoshop to edit it to say "50% off your year books with this QR code". The QR code then linked to a gorilla eating a taco (google this its pretty funny), adding to confusion. The year book committee had a FREAK out and sent out a mass email that the QR code was fake and not to follow it and you COULD NOT GET 50% off a year book no matter what link you followed. Needless to say sparked more interest in said QR code and soon the whole school had loaded a gif of a gorilla eating a taco.