The frog robot condom

Peter Narins needed a way to convince real frogs that a male intruder has just hopped into their territory and is croaking boldly. So the animal communication researcher came up with the obvious choice: condoms. In 2000, Narins, a professor at the University of California, Los Angeles, and his colleagues at the University of Vienna glued a condom to the jaw of a robotic frog equipped with an air pump and speaker. It worked: The condom makes such a believable vocal sac that the robot, despite its immobility, can incite a real frog to spar.