Trump’s elevation in the “idiot” results is, according to the Guardian, the result of a deliberate campaign to manipulate Google’s algorithm.

It all started naturally, as Green Day’s song American Idiot was heavily used during the recent protests at Trump’s U.K. visit. But then, users of the Reddit forum site apparently started upvoting a post that contained Trump’s photo alongside the word, in order to tell Google that the post’s page is popular and therefore probably relevant to people searching for “idiot.” Of course, every time an article such as the Guardian’s—or this one—appears, it reinforces the trend.

This is a phenomenon known as Google bombing, and it’s a function of the simple fact that Google’s search algorithms take popularity as a major indicator of relevance. And it’s nothing new.

The first Google bomb allegedly occurred in 1999, when a search for “more evil than Satan himself” would bring up Microsoft’s website. Other examples since then have included returning British Prime Minister Tony Blair’s biography for the search term “liar,” having a search for “terrorist sympathizer” throw up Bill O’Reilly’s homepage, and giving those searching for “dangerous cult” a top link for the Scientology website (thank the hacktivist group Anonymous for that one.)

Very memorably, in 2003 the sex columnist Dan Savage responded to deeply homophobic remarks from politician Rick Santorum by creating a website that ensured searches for Santorum’s name would throw up the definition: “Santorum: The frothy mix of lube and fecal matter that is sometimes the byproduct of anal sex.” The reputation of Santorum, who did not find this funny, never quite recovered.

And not all Redditors use the tactic to attack the right. Members of the TheDonald Reddit forum managed to game Google’s system before the 2016 election so that a search for “rapist” would bring up images of Bill Clinton. They did the same for CNN’s logo, returned to those searching for “fake news.”

Of course, Google bombing campaigns only work as long as those involved keep trying to promote them. Once the “joke” has worn thin and people stop trying to game Google’s algorithms in a particular direction, those algorithms will start to find other pictures or websites more relevant, and something else will take over at the top of the results list.

All this is a reminder that, while search services try to reflect the reality they perceive, in an ideologically neutral way, that perception can still be tricked—for a while, at least. As soon as people stop trying to associate Donald Trump with idiocy, the problem will go away by itself.