HU’S ON FIRST. Chin-lung Hu is a utility infielder who has been playing in the majors from time to time from 2007 with the Dodgers and this year with the Mets. Here are his stats from fangraphs. He has 190 at bats in the majors so far. I saw recently somebody—I can’t remember who or where—pointing out that every time Hu singles or walks, one could say: “Hu’s on first.”
Here from Baseball Almanac is the script of the Abbott and Costello routine that popularized the phrase “Who’s on First.” And here is one of the ways that Abbott and Costello performed it. This wikipedia article says that “Who’s on First” is descended from turn-of-the-century burlesque sketches with different settings.