This Acronym, derived from OMG and ROFL simply adds to the expression by adopting MAO, otherwise known as, (My Ass Off.)
In effect, this expresses the writers in the following way.
Oh My God - Rolling On Floor Laughing My Ass Off.
As you can see, this acronym saves a tremendous amount of time typing, and allows others to join in the fun faster than had the writed actually spelled this out.
Andrew (DarkEye): Oops, did I type that in the channel?