It's no secret that the energy stored in citrus fruits can generate an electrical current (a favorite demonstration of middle school science teachers). But what happens when you use 2500 oranges? You can power a neon billboard, apparently. [Mashable]
Not to be a buzzkill, but that is DEFINITELY not neon. Neon does not bend like that. That's a flex LED strip meant to mimic neon, but uses a fraction of the energy. So this should read "how many oranges does it take to power an LED billboard".
example- Jesco makes a COLORFLEX led strip (their website sucks so I can't link it, just google it :) )
edit: these LED strips use about a tenth the energy of traditional neon... so a neon sign would have about 25,000 oranges for a similar effect.