A person who is sitting too much at his computer.
The person is very skinny because of the lack of time to eat since the person is always playing games and don't have time for bullshit like eating.
The persons back is also very bad because the person is sitting so close to the display so the back kind of gets a new shape.
His/her behaviour is mostly often very geeky. With other words, a real nerd.

A portmanteau of carpe diem, a Latin phrase that means “Seize the Day!” and DM, which stands for Direct Messages. This word means seizing the day via DMs.