I am SO sick of lol in internet chat. For those who don't know, lol is short for laughing out loud, and people say it all the time. I see entire conversations that are like:
person #1 "That was crazy!"
person #2 "Yeah, lol"
person #1 "lol"
person #3 "lol"
person #4 "rotfl"
person #2 "lmao"

rotfl is rolling on the floor laughing, and lmao is laughing my ass off.

If you aren't actually doing those things, laughing out loud, rolling on the floor, or laughing so hard your ass actually starts coming off of your body, don't use these expressions. While they may appeal to your average moron, anyone with a brain immediately discounts you intelligence level.