"Laugh To Myself" - because not everything funny warrants a LOL; also, more suitable form of laughter when at work or the school library where 'laughing out loud' is frowned upon; and, let's face it, LOL is played out and just all-around obnoxious.
Friend - "wut up?"
Me - "nothin. bored at work"
Friend - "at least you have a job"
Me - "LTM"
Brain herpes is something unpleasant that you haven't thought of in a while that pops into your head every once in a while. You can't unsee it, unhear it, etc. Once you contract a brain herpes, it is with you for life.
Examples of brain herpes include: goatse, that fucking Barbie Girl song, the image of when you walked in on your parents mid-coitus, etc.