Even if they hadn't engineered a dick in a lab, the researchers at the Wake Forest Institute of Regenerative Medicine would already have been justifiably famous for successfully transplating lab-grown vaginas in four patients. But the team are looking to build on their success by bioengineering fully functioning penises that could be ready for human testing in as little as five years. 

Professor Anthony Atala told the Guardian that the transplant penis is partially grown from the patient's own cells and says that the prosthetic organ would benefit men who suffer from genital defects, penile cancer or traumatic injury. Rabbit wang transplants have so far proved highly successful, although FDA approval remains some way off. 

Atala and his team of scientists are currently testing twelve lab-engineered human penises, which includes putting them through a machine that "squashes, stretches and twists them to make sure they can stand up to the wear of everyday life".

"It’s a rigorous testing schedule," Atala said. "But we’re trying to get approval from the US Food and Drug Administration so we know everything is perfect before we move to a first in-man test."

We give it about three years until some ambitious amateur scientist tries to biohack his way to a second penis.