I received a private message asking for help on deciphering one such code, and decided to share the little I have learned with the other uninitiated people who might join in if they didn't feel either out of their liturgical depth or unfamiliar with the genre.
The culprit, ROTFL, means "rolling on the floor laughing".
Another culprit, which I think is peculiar to SSG circles, is IMH(BC)O, meaning "in my humble (but correct) opinion".
As I discovered on a recent posting, you can unwittingly make emoticons by certain combinations of keyboard characters, such as 8 followed by ) which gives

So now you can sit up into the wee small hours and play a game, trying to work out the keyboard codes for all the emoticons on offer, and trying to work out a new one to stand for "sympathy".
After that, you might turn your mind to what are "good" songs IYH(BC)O, and add to the thread which is not quite spinning yet. If you make absurd suggestions, you might have us all ROTFL!