In Britain's Parliament, the ongoing debate about leaving the European Union has descended into ugly insults and jeers. For example, on Tuesday, Jeremy Corbyn, leader of the opposition Labour party, was telling his fellow lawmakers about a recent trip to Europe. "Last week I was in Brussels," Corbyn began, "meeting European leaders and heads of socialist parties. And one of them said to me…"

Out of nowhere, a Conservative member of Parliament shouted: "Who are you?" Britain's most important politicians descended into a wave of giggles at the insult. Corbyn was unable to continue speaking for another 30 seconds.

That wasn't an isolated incident. On Wednesday, British Prime Minister David Cameron was talking about proposed budget cuts when a Labour MP shouted at him: "Ask your mom!" It was a reference to the fact that Cameron's own mother had signed a petition opposing the cuts that her son, the prime minister, supported.

Cameron quickly fired back with an insult about Corbyn's attire, even though Corbyn himself had not actually mentioned his mother. “Ask my mother?” the prime minister responded quickly. “I know what my mother would say. She’d look across the dispatch box, and she’d say, ‘Put on a proper suit, do up your tie, and sing the national anthem!’” (The last bit refers to the left-wing Corbyn's reluctance to involve himself in displays of nationalism).

Even Boris Johnson, the media-savvy Conservative MP and mayor of London who has endured years on various British comedy panel shows, found himself on the receiving end this week. As Johnson, a major voice in the campaign to leave Europe, stood up to speak on Tuesday, he was greeted by a wave of moans and an obnoxious order: "Tuck your shirt in, Boris."

An outsider might wonder what exactly was happening here: Has the bitter debate over a "Brexit" from the E.U. finally broken down British manners?

Not exactly: British politicians have been doing this for a rather long time. The House of Commons — and in particular, the weekly Prime Minister's Question time – have long been a breeding ground for some of the most inventive political insults seen in the world. The current prime minister has proven particularly inventive at the insults, branding Corbyn's predecessor Ed Miliband a "complete mug" and former Labour shadow cabinet minister Ed Balls both a "muttering idiot" and "the most annoying person in modern politics." Miliband got his own shots in, too, calling Cameron "the dunce of Downing Street" among other, less cutting, insults.

There have been scores of other inventive abuses over the years. In 2013, former transport minister Simon Burns was reprimanded after being reported to have mouthed “stupid, sanctimonious dwarf" to diminutive House of Commons Speaker John Bercow (he later apologized to dwarves). In 2010, Labour MP Tom Watson shouted across the room to his Conservative colleague Michael Gove, "You're a miserable pipsqueak of a man." British Prime Minister John Major suggested his then-rival, Tony Blair, was a "dimwit" in 1995, while Blair later told Major he was the "weakest link." In the 1980s, Labour MP Tony Banks said Margaret Thatcher was acting "with the sensitivity of a sex-starved boa-constrictor," while MP Dennis Skinner called one of his rivals a "pompous sod" (and then offered to retract the word pompous, but not sod).

Insults in Parliament go back a long, long way. One (possibly apocryphal) story suggests that Benjamin Disraeli, the famously quick-witted politician of the Victorian era, once told Parliament that half of the cabinet were asses. When asked to withdraw his comment by the speaker of the House, Disraeli supposedly responded: "Mr. Speaker, I withdraw. Half the cabinet are not asses."

Why are British politicians so mean to each other? That's hard to say. It could be due to the adversarial design of the House of Commons itself, where the government MPs sit glaring at the opposition MPs and vice versa. Famously, the distance between the two front benches is said to be slightly more than two sword lengths, designed to stop sword fights. Additionally, many of the MPs view their acerbic wit as a key part of their appeal, having honed their skills on the Oxbridge debating circuit.

And while the House speaker may reprimand those throwing insults, throwing them out of Parliament if they don't withdraw them (accusing a colleague of lying is viewed as particularly heinous), the speaker often giggles at the insult and lets it carry on. And as Britain entered the age of rolling cable news and social media memes, the number of insults seems to have increased. Politicians have become aware that a quick insult might be a better way to gain popularity than a serious debate.

In fact, Corbyn is unusual in his commitment to moving away from scornful remarks about his rivals. "I don’t do personal attacks," he told the Guardian last summer. A few months later, however, even he was insulting Cameron. Well, kind of — someone had broken into his official Twitter account to offer an unfavorable judgment on the prime minister: "davey cameron is a pie."

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