Definition
To do anything disappointing; to fail significantly.
How People Actually Use It
To do very badly at life. It is much worse than just sucking. You should most likely kill yourself if you fail at life. It is your best option.
"Person1: I have a myspace! Oh my god! I posted a pic of me looking in a random direction and I have a lot of E-Friends! Person2: You fail at life."
Source: Urban Dictionary