Hedge fund assassin David Einhorn scaled Green Mountain Coffee ( GMCR) in front of a live audience Monday. Unfortunately for a few bullish analysts, he scaled it like a fish as opposed to a mountain. Speaking at the 7th annual Value Investing Congress, Einhorn filleted the high flying maker of Keurig single-cup coffee machines in a 110-slide Powerpoint presentation titled "GAAP-uccino". Of course, the assembly of hedge fund managers who paid big bucks to hear Einhorn didn't wait until slide number two before opening fire on the stock, sending it down more than 10% by day's end to $82.50. Aside from taking the company's financial disclosures and capital spending to task, Einhorn, who gained market-mover status by mauling Lehman Brothers in a similar manner, said that using one of Green Mountain's single serve cups "is a very expensive way to drink coffee at home." Honestly, we're not sure about that particular contention unless he is comparing it to brewing up a pot of Chock full o'Nuts in dad's old Mr. Coffee machine. Nevertheless, it's hard to fault Einhorn's other calculations because you just know the man does his homework. And if bringing down Lehman was not proof enough of Einhorn's research prowess, simply check out the 40% drop in shares of St. Joe ( JOE) since he proclaimed the Florida land bank a short candidate in a 139-slide presentation at last year's conference. Right now the big loser on the other side of Einhorn's St. Joe trade is mutual fund manager Bruce Berkowitz, who has vainly (in both senses of the word) fought back by loading up on even more shares of the company. In the case of Green Mountain, Einhorn's challengers include Akshay Jagdale of KeyBanc Capital Markets and Janney Capital Markets' Mitchell Pinheiro, both of whom defended the company in research notes released Tuesday. Jagdale reiterated his buy recommendation, saying that Keurig single-cup coffee machines will climb from around 8% of U.S. households currently to 22% by 2013, no matter how many slides Einhorn shows his hedgie buddies. And Pinheiro also reaffirmed his buy rating, while criticizing Einhorn for ignoring "factual evidence of strong market takeaway performance in the housewares and coffee categories." Jagdale and Pinheiro also restated their price targets of $120 and $125 respectively for Green Mountain shares clearly steep climbs in the current environment for such a highly contested stock. And while Einhorn may not win every contest he enters -- for examples, see Yahoo! ( YHOO), New Century Financial and the New York Mets -- he does tend to create more than his share of losers, which is why Messrs. Jagdale and Pinheiro may want to have a coffee klatch with the company before this coffee clash with Einhorn boils over and burns them.