BY MATTHEW PRICEFeatures Editor mprice@oklahoman.com Osage Beach, Mo. — Thom “Gabby” Gumm has been entertaining visitors to the Lake of the Ozarks for more than 40 years, providing laughs with his skits, songs and impressions of everyone from Donald Trump to Chuck Berry. At the moment, though, he was bonking me on the back of the head with a soft mallet ...