LOLOI - means something is funny enough to use LOL for, but you only laughed on the inside of yourself because you were in an inapproriate place. "Laugh out loud, only inside".
My friend sent me a vial, but hillarious joke while I was at the Library. I almost lost it with laughter but I had to keep my laughter hidden within since it was a quite area. I didn't know how to respond so I put, LOLOI (since I really only laughed inside, but it was funny enough to LOL). It's been spreading ever since.