In Baisers volés, Delphine Seyrig explains to her young lover the difference between politeness and tact: ‘Imagine you inadvertently enter a bathroom where a woman is standing naked under the shower. Politeness requires that you quickly close the door and say, “Pardon, Madame!”, whereas tact would be to quickly close the door and say: “Pardon, Monsieur!”’ It is only in the second case, by pretending not to have seen enough even to make out the sex of the person under the shower, that one displays true tact.
The too intellectual for me Slavoj Žižek in Good Manners in the Age of WikiLeaks