It's a nightmare that has probably kept plenty of astronauts up at night - falling out into space without wearing a proper suit.
The assumption, based on movies and TV shows, is that you'd pretty much instantly die, but the reality is a little more complicated than this - as a simulation posted to YouTube has demonstrated.
It immediately confirms that despite pop culture telling us otherwise, you "probably wouldn't explode" - although it does take the chance to show that process in a nice little gory moment.
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Instead, according to the simulation, the gasses in your body immediately "will start to expand", and this process very quickly "will cause your lung tissue to rupture".
As this continues, it will only take five seconds for "water on the surface of eyes, skin and mouth" to start evaporating, with the water in your very blood starting to boil.
That's quite terrifying, and it has the effect of basically swelling up the whole body to the limits of your skin's elasticity - thankfully this is nearly the end of the ordeal.
From here you'd apparently pretty swiftly black out, and after this point, the heart would slow and stop before you died of asphyxiation - which is perhaps a more gradual process than you'd probably assume.
And the video is impressively backed up by more detail from Popular Science, which confirms that your blood would vaporize in the first 10 seconds in the vacuum of space, and all the water in your body would follow suit in the first 15 seconds.
This would be immediately followed by a loss of consciousness as the lungs collapse and the body expands, and death would be almost inevitable within 30 seconds, either by asphyxiation or decompression.
Of course, knowing that this is how things would go doesn't really protect you from it - if you're ever in the vacuum of space, chances are that it's too late to do much about it.
Equally, most of us will never be at the slightest risk of this event, thankfully, something the comments under the YouTube short have been pointing out amusingly.
One person wrote: "Props to the guy who went to space for us to know all this," while another said: "'It's better to breathe out the air immediately' I need to remember that,"
Most people, though, are obsessed with the brief window when your swollen body would look almost muscly: "This video shows how to become buff in seconds."
That's a positive way to look at what would be a pretty horrific death, but then again that's how the internet works - someone's always cracking a joke.