Out of context Loss is actually pretty good, frankly. The thing is the context it was found in doesn't deserve it. It came from a sub-boner humor gamer comic that suddenly got really dramatic. The tone whiplash just struck a nerve at the time, which is why the comic came to wide attention.

Then there's the "is this Loss" meme, which is kind of a prank game where you encode the layout of Loss as abstractly as possible, often with one line, to represent the character walking through the door alone, two lines, one tall and one short to represent him standing and the sitting nurse, two tall lines for him and the doctor standing, and then one vertical and one horizontal line to represent him standing and her lying down. The joke here lies in reminding people of this stupid thing in as abstract and distant a way as possible.

Do you "get" rickrolling? It's the same thing