If you work in an open office environment, you’ve no doubt instant-messaged a colleague with something funny, and they replied with LOL (laugh out loud).
But then, if you sit near this person, you look and listen and realize they aren’t really laughing out loud. So why write it? It’s not like you can’t see.
Perhaps we’ve gotten lazy with our acronyms.
May I suggest TAM (that amuses me). That would lower the expectations of the originator of the presumed humorous comment and add some accuracy to the result.
Or perhaps LIMH (laughing in my head). This tells your friend that you found the comment funny, but for some reason, perhaps you didn’t want to disrupt coworkers, you kept the chuckle to yourself.
Language is important. Let’s try to be accurate with it.