'Leet Speak' or 'L33t 5p34|<' supposedly developed among paranoid hackers as a method of communication to avoid filters/monitoring. It was popularised by gamers and other wannabe geeks, especially 12-15 year olds. It's a fad that's getting pretty tired... hence "only lamers speak leet".
I used to play an online role playing game called 'Anarchy Online'.. and the lowest creatures in the game were called 'Leets'. They would taunt you with "stfu mofo" ... "r u nubi?" ... "phear me" ..."i'm uber" ... "u suxxor" ... "i ownz joo" ... etc
