In a desperate attempt to stop the sale, Alan does something incredibly stupid. He hires a private investigator to dig up dirt on Walden. The P.I. (played by The Big Bang Theory ’s Johnny Galecki in a hilarious cameo) actually finds something: Walden’s old business partner, whose name Walden accidentally omitted from a lucrative patent years ago.
This leads to the final scene, which is perhaps the most talked-about moment of the episode. The screen cuts to a production backlot. We see Chuck Lorre himself, sitting in a director’s chair. He says, "Winning," a clear reference to Charlie Sheen’s famous meltdown catchphrase, before a second piano falls on him . Two And A Half Men - Season 12Eps16