But if you think they are going down, you now have no way to short.

Borrow Bitcoins. Sell Bitcoins. Congrats, you are now short.

Seriously, I LOLed about this......

That's just one part of short... you wait til it goes below 10 and buy back the coins.. and u keep the difference.. that's the short...

Yeah, or your lender calls the mafia to help collect on your loan and you need to pay more than you sold them for... that's the short squeeze