What happens in tonight's Love Island lie detector test episode?

In what is always one of the most explosive episodes of the whole run, the remaining couples will be put under pressure as they're hooked up to a polygraph and asked a whole load of probing questions.

For example, the teaser for the episode shows Josh being asked: "Will you stay loyal to Kaz on the outside?"

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https://www.youtube.com/watch?v=d5arf3DrUD0&list=PLbs-Pk9dtKb_6P7X6mxinrr4yDvKKs39v

Although we don't know how he answers, Josh does say "bloody hell, I'm sweating" as well as "oh s**t". And this is Kaz's face:

So, well, it doesn't look good.

But for the uninitiated, what usually happens in the lie detector? And is the test genuine?

Well last year provided us with some amazing moments, including Liv and Chris having a gigantic falling out before the lie detector had even started. No surprise there.

https://www.youtube.com/watch?v=Fdf8s4d4xto

The islanders take it in turns to be hooked up to a lie detector machine in another room, usually the Hideaway, while the other islanders gather around a TV to watch what unfolds...

Each couple take it in turns to set questions for their other half, and ask things such as whether they see a future together outside the villa, are they loyal (we wish we could've seen Georgia answer this one) and whether they're actually in love with their partner.

The big question fans were left asking last year, however, was are the lie detector results faked? Last year, RadioTimes.com was assured that the results were 100% genuine, however the method of polygraph testing and its reliability is always disputed and the results are not admissible as evidence in court.

Meanwhile, 2016 star Kady McDermott claimed on Twitter that the producers chose "who to fail and pass" the test:

https://twitter.com/kadymcdermottx/status/887411852531179520?ref_src=twsrc%5Etfw%7Ctwcamp%5Etweetembed%7Ctwterm%5E887411852531179520&ref_url=https%3A%2F%2Fwww.radiotimes.com%2Fnews%2F2017-07-19%2Fwere-love-islands-lie-detector-results-faked%2F

Well whatever happens, the revelations that emerge always cause plenty of fireworks, so it's definitely an episode not to be missed.

Love Island airs daily at 9pm on ITV2