I smell a troll here, but I'll answer it for the sake of answering it.
I Don't Know
Yes of course just stop texting. If you know you shouldn't be doing this then stop.
LMK in texting language means "Let Me Know".
Like
I know
- well the thing is, are they texting you back?- you probably miss them
it means "you know"
It means I Know in texting/SMS/chat.
Let Me Know
i also dont know
It is not free unless you have a texting plan. I know it sucks =/ IT costs 20 cents per text and 25 per picture. :(( ;'(
You know, a lot of teenagers are addicted to texting. They think that was cool. So I think texting changed teenagers.
It could mean 'I know nothing'