drop trou Share definition Flag To lower one's pants down to one's ankles, often in a sudden, impulsive manner, thus exposing one's nether regions. We all dropped trou and mooned the old lady. drop trou by Stan B. February 4, 2003 Word of the Day on May 6, 2024 0 0 Get merch Get the drop trou mug. Buy Now — $32.95 See more merch