Women are generally socialized to take up as little space as possible -- to shrink in size, even, to make those around us more comfortable. Those who manspread participate in exactly the opposite behavior.
Manspreading is when someone, usually male, opens his legs widely as to take up several seats, generally apathetic to the inconvenience his excessive space-taking has on others. While the phenomenon is most often observed on public transit, it may take place just about anywhere a man might be.
The women of BuzzFeed decided to conduct a little experiment in "manspreading," taking up as much space as possible to see how it felt. For the most part they succeeded in their mission, though it turns out that taking up excessive space isn't always as comfortable as it looks.