Ervin Frank "Four Sack" Dusak (July 29, 1920 – November 6, 1994) was an American Major League Baseball player. Born in Chicago, he was signed by the St. Louis Cardinals in 1938 and got his nickname from a poem a fan wrote after he hit a home run in the minors. He was very briefly with the 1941 Houston Buffaloes of the Class A1 Texas League, who won 103 games. He earned cups of coffee in the majors with the Cards in 1941 and 1942 and then returned to the club from 1946 to 1951. He mostly played outfield for them, with some games at second base and third base. On July 7, 1946, he hit a game-winning, three-run home run to beat the Brooklyn Dodgers and to move his club within a half game of the National League lead. The Cardinals went on to win the World Series, and Dusak played in 4 Series games, getting 4 at-bats and hitting a double in Game 2.
Dusak saw his most big league action in 1947, hitting .284 in 111 games. He drew walks well, with a lifetime .334 on-base percentage that was 91 points higher than his batting average. When his batting average dropped, he turned to pitching for a while (appearing in 23 games), but ended up his career primarily as a position player with the Pittsburgh Pirates.
After retiring in 1952, Dusak was an insurance agent for 21 years and worked in a bowling alley for a decade. He died in Glendale Heights, Illinois, aged 74.