In the most 'genuine' of situations, it is proclaimed to a newer player by a veteran who does not have the patience to take the time to help.
In more ironic situations, a losing player will use it as a protest against tactics that he/she finds 'unfair' or 'newbish'
player 2: omg l2p noob
b) "Omfg l2p and stop camping." said after being shot three times by the same player, hiding in the same spot, in a first-person shooter.