"Dr. Jeff" is not a glib radio moniker. Jeff Hallazgo is a bona fide doctor — specifically, the attending physician at Des Peres Hospital's emergency room. His show, The Big Bang! which airs every Wednesday from 4 to 7 p.m. on KDHX (88.1 FM), is a rollicking romp through an hour of R&B, followed by two hours of pop. What makes Dr. Jeff so endearing on the air is that he's both slightly nerdy and head-over-heels in love with these tunes. And for all his esoteric knowledge of music history, he's no snob: After throwing in lesser-known tracks from the O'Kaysions and the Royalettes, he'll pay homage to such greats as Marvin Gaye, Aretha Franklin and, yes, the Monkees. His love has spilled over onto other platforms, too. He's constantly updating his page on the radio station's website with historic pics and videos. He interacts with his fans on Facebook. And he's tweeted out some LOL-worthy nuggets, such as, "Trying to do this P90X fitness program, but the ice keeps falling out of my glass." See? Even doctors blow off workouts — and know how to kick it old-school on the radio waves.