Why the first comment is called a sofa grab

The landlord sent the main post to indicate the theme of the forum, and then invited friends to come in and talk, the host - the main floor to entertain guests, of course there will be sofas, benches, etc. to entertain guests, but there are too many guests, and to treat all guests equally, so you can only respect the first to come, the first to come (the first reply) can sit on the sofa, and the second can only sit on the bench, the third is the floor.