There is one sexual gaffe that out-gaffes all other sexual gaffes, and we all know what it is, so let's cut to the chase. It's the mid-coital fart (aka the sexual guff), loud and proud. Many women think that their partners have suffered occasional impotence. Not so. The chap in question feels the mid-coital fart coming on in that irresistible way that only mid-coital farts command, and are so obsessed with holding it in that they lose, er, pencil lead. The usual excuse for the ensuing drop in performance is that you've done your back in. Here endeth sexual gaffes - lesson one.