The first time I heard the term "lol" I was 10 and didn't know what a riot the world really is. Since then, my humorous vernacular has expanded dramatically, allowing me to communicate just how funny I think things are through a variety of socially acceptable internet acronyms. Below I give you the guide to the infamous LOL.
1) lol: To be used when someone attempts a funny joke, but you do not actually think it is funny, so no laughing-out-loud actually occurs.
JOSH: my dad can make some pretty biting remarks
JESS: must run in the family
JOSH: apple, meet tree. don't fall from it.
2) LOL: To be used when you actually do laugh out loud, but only slightly: perhaps a whispy giggle, or the mere beginnings of the onset of true, laugh out loudum.
Example: Dancing horses.
3) LMAO: To be used when your roommate can hear you laughing in the next room over. Usually follows a self-depracating joke, something found on gawker, or when something awful befalls a person you detest.
4) LMFAO: Only to be used when high, and watching Youtube. Specifically, this video.
Warning: Never, EVER employ the term "ROFL." The only people who use this term are people who use these kind of smiley faces:
^__^ <__> -__-