Something that occurs from time to time in science fiction is that someone winds up in a vacuum without the benefit of a space suit. Think:

“2001” Astronaut Bowman without his helmet

“Outland” Several people blow up like balloons when pressurization is lost

“Star Trek: TNG” Bev and Geordi survive a few seconds in a depressurized cargo bay, long enough to hit the “close the damn door and turn the air on” button

“Mission to Mars” where Mr. Tim Sarandon opens the visor of his helmet and promptly freezes solid.

“Guardians of the Galaxy” where a few character wind up floating outside like a couple of jackasses

But what *really* would happen to someone? Fortunately, Geoffrey Landis has a page devoted to just that question:

Human Exposure to Vacuum

The short form… you have between five and 12 or so seconds of useful consciousness at best. In ninety seconds, your heart stops and you’re dead as disco. Do you freeze solid instantly? Nope. Do you pop? Nope. Does your blood boil? Nope. You just turn blue, your eyes get bloodshot, you flail about for a few seconds and then you die. Not nearly as dramatic as generally depicted.

If you are a sci-fi writer, you now have no good excuse for getting it *really* wrong. Of course, if the victim’s blood is loaded with anti-bacteria Buckeybombs, I guess it’d be okay to have ’em pop in a vacuum, so long as there’s a valid link between the vacuum and the detonator…