The phonetic spelling of perhaps the most common internet abbreviation, lol. Since lol is an abbreviation to shorten the word, spelling out the expression shows that the term is being used with either sarcasm or great emphasis.
Generic 12 yr old: OMG THATS SO AWSOM!!! LOL!!!!11
Mature user: Wow! You got to level three! Ell oh ell!
Mature user 1: tells funny joke
Mature user 2: Ell oh ell, that's the best thing I've heard today.