This is the picture posted as the default profile picture on any social media website, i.e. Facebook, Twitter, Tumblr etc., that is a picture of a "bro" with his shirt off flexing in the mirror, or flexing on the beach.
"I just uploaded my new brofile pic, check out how big my muscles look in the mirror."
"Take a picture of me on the beach so I can set it as my brofile pic to show off my abs."
"Eh breh, it's time to hit the gym to get that brofile pic for the ladies."
This is the act of being skinny and fat at the same time, or being skinny but out of shape. Someone with skinny extremities who also has a beer gut would qualify as finny.
"That chick looked hot from here, but when we got closer we realized she was just finny."
"Check out the finny dude with his beer gut."