This is a new term, and is not made up.
Here is the definition of man spread or man-spread:
when men take up too much room on the subway by spreading their legs in a wide v shape. Also, dangling your legs to take up extra space while seated on public transit or draping your legs across multiple seats.
I seldom ride public transit so I did not know this was a major problem but it is in large cities. Apparently, an average chair is 17.5 inches wide, and this is home much space one should occupy on a bus or subway.
Some people are taking up more than their allotted space. This can also be called bench hogging.
In Philadelphia signs on their transit system read “Dude it’s rude . . . Two seats — really?” The New York’s Metropolitan Transportation Authority (MTA) just launched an etiquette ad campaign that includes cartoon posters of a spread-eagled transit rider that says “Dude . . . Stop the Spread, Please. It’s a space issue.”