Revealing your "private parts" to another person ie. whipping out your penis showing your tits. Flashing definition, Building Trades. pieces of sheet metal or the like used to cover and protect certain joints and angles, as where a roof comes in contact with a wall or chimney, especially against leakage. See more. Flashing definition: a weatherproof material, esp thin sheet metal, used to cover the valleys between the | Meaning, pronunciation, translations and examples.