Just read about this orangutan called Fu Manchu who allegedly crafted a self made key for his zoo cage, kept it hidden in his mouth all day and regularly escaped during the night.
Mother Nature Network - Hairy Houdinis: 6 animal escape artists
High-tech surveillance was the only way that zookeepers were able to keep up. Long after zoo employees had left for the night, Fu would climb into the air vents connected to his enclosure and follow them to a dry moat surrounding the orangutan exhibit. Inside the moat was a locked door that employees often used. The clever ape would pull out a small piece of metal wiring that he kept hidden under his cheek throughout the day, and proceed to pick the door's lock!
Is this real?