Broken plastic Atwood hot water heater drain plug

So a small leak turned into a complete drain. The plastic bolt on the bottom of the hot water heater was leaking. In an effort to clean the bolt and then wrap it with teflon tape and reinstall it, it was still leaking a but so I tightened it a smige...just a smige...and it snapped off :S Now I can get the replacement plastic bolt, but how do I get the rest of the plastic bolt threads out of the hole?