RIDGEFIELD — David Watson is the kind of guy who calls his buddies “cats.”Cats like Dizzy and Miles. Monk and Hawk. Nat and Frank. Watson met all those famous cats, he said, and played or sang with many of them. The one jazz legend he really wished he had met, but never did, was Ella Fitzgerald. Watson was just a child, growing up with a singing father in a musical household, when he heard Fitzgerald’s peerlessly acrobatic scat singing. Scat singing means transforming your voice into something like a saxophone and bebopping your way all over a melody, just like an instrumental soloist. Fitzgerald’s famously fast, fearless, joyous jazz explorations inspired Watson’s own scat singing as he grew into the nickname he now wears proudly: “The Doctor of Bebop.”Watson grew up in Philadelphia, served in the Army, returned and tended bar at the downtown Showboat Jazz Theater. It was the chance of a lifetime, he said, where he not only hobnobbed or jammed with all those jazz cats, he even stole some moments behind their drum kits. Some of the greatest drummers on the planet — Max Roach, Art Blakey, Tony Williams — “Anybody who played at the Showboat, I played their drums during the daytime,” Watson confesses in a short interview film made last year by Steve Anchell for the Northwest Jazz and Blues Project.“I have great, warm, wonderful memories of some of the greatest musicians. I got to hang with them. It was a wonderful life,” he said.