A technique used by creative exhibitions to show off their penis and testicles. The technique involves squeezing your balls and member through your legs, then bending over and revealing the product from behind. It gets it's name from the product forming a trunk and wrinkly brains. It's kind of like the mangina, but from behind.
Bob: "Hey Gary, come in here, I gotta show you something."
Gary: "What the hell do you want... Ahhh, not the Elephant Brains again, you sick bastard!"
Bob: "Don't act like you've never seen my shit before."