By Michael Tedder And you can wash it down with all the soda you want, all month long. There was a time when using auto-tune to correct your pitch was considered a cheat, not something real singers would do. But then T-Pain appeared and changed the game. The rapper, singer, producer and auteur behind such hits as “Buy U a Drank (Shawty Snappin’),” “I’m ‘n Luv (Wit a Stripper)” and “Bartender” brazenly coated his vocals with so much auto-tune that it became an aesthetic and not a crutch, dazzling the late ‘00s with a woozy croon that Kanye West and many others emulated. Fans of the man born Fah…