Borrowing from a somewhat-obscure ‘Flying Circus’ sketch…
If you ever find yourself in an argument with someone over something that you are sure you’re right about, and they insist they’re right when they’re completely wrong, AND they refuse to consider your opinion, AND they get really nasty and mean about it, consider this useful conversation ender before turning and calmly walking away:
“What do you know about it? What do you know about getting up at five o’clock in t’morning to fly to Paris, back at the Old Vic for drinks at twelve, sweating the day through press interviews, television interviews and getting back here at ten to wrestle with the problem of a homosexual nymphomaniac drug-addict involved in the ritual murder of a well known Scottish footballer???”