As you see above, some people claim LOL means 'laugh out loud'...ie it's an instruction to the reader. Others think it means 'laughing out loud'...ie it's a statement of what the writer is currently doing.
Whichever of these you go for, it is clearly nonsensical. You can't TELL someone to laugh out loud unless you are a bit daft yourself and, even though you laughed out loud when you first saw the funny item being referred to, it is highly improbable - now that you have got around to writing about it - that you are still doing so.
In whatever circumstances it is used, it is either absurd or untrue. Best avoided, therefore. Otherwise, Why not use the not-much-more-complicated ILOL = I laughed out loud. That is, the writer considered the thing amusing and imagines others will do likewise. Simples!