Boo Yeah! Share definition Flag Catch phrase of men with no testicles. Usually shouted upon premature ejaculation. Girl: Hi! I'm Stacy! Guy: BOO YEAH! Girl: I drive a red moped. Boo Yeah! by slickownzyou March 1, 2003 0 0 Get merch Get the Boo Yeah! mug. Buy Now — $32.95 See more merch