LolZzZZz is just another way of saying LOL or the very simple LOLZZ but in a more extreme way . It shows more of histerical laughter then a simple "hehehehahaha" . Actully , this internet slang was created by a typo .

the art of remembering an arousing occurrence or some porn you watched while masturbating, often handy if you have no porn or your in the shower