Couchsurfing is a neologism referring to the practice of moving from one friend's house to another, sleeping in whatever spare space is available, floor or couch, generally staying a few days before moving on to the next house.
The company, its website, and the culture of hospitality exchange it is meant to support are all commonly referred to as "Couchsurfing" by the website's userbase, though sometimes the "s" is capitalized.
People who use the Couchsurfing.org website frequently refer to themselves as "couchsurfers", "surf