Johnny Canales gleamed in one of his signature shimmery jackets, a white cowboy hat atop his head and a big smile on his face. He waved at revelers below who’d gathered last December to see the floats decorated with Christmas lights, poinsettias, and tinfoil as they swanned through downtown McAllen. The border city’s annual holiday celebration, now in its eleventh year, is the largest of its kind in Texas—the state’s answer to the Macy’s Thanksgiving Day Parade. As Johnny passed by, many in the crowd whooped when they spotted the beloved television host who, beginning in the eighties, introduced them to cherished tejano stars such as Ramón Ayala and Selena. From the sidelines, some yelled his famous catchphrase: “You got it, take it away!” Frail from…