Johnny is one of a select group of people who think they contain a vast well of knowledge on all subjects. Like Cliff Clavin the character on the old TV show Cheers, he pretends to know intimate details about everything—from the best region for the manufacture of shoe polish to the calibration of gene splicing equipment. Johnny works as an hourly employee in a large corporation and has no specific higher education or degree.
Greg: "I have a stomach ache."
One up Johnny: "That pain in your abdomen could be from a variety of internal organs. These organs include the stomach, small intestine, colon, liver, gallbladder, and pancreas. It could be a serious condition. You should consider being evaluated by a physician"
Greg: "Yeah, or it could be from that donut I ate earlier."