A near neighbour is on the phone to my husband. He asks some relatively mundane advice, which is given.
Still on the phone, the neighbour shouts to his wife "It's your fault, you're so bloody stupid". A huge row develops between these two, people we have always considered to be ultra-polite, perfectly mannered etc., - and still on the phone. My husband could hear every - single - word.
What on earth do you do? Pretend you don't notice? Put the phone down?