tweet: Millennials use "lol" like STOP at the end of a telegram lol
tumblr response: REGRET TO INFORM YOU YOUR SON HAS DIED FROM TRENCH FOOT LOL HE SERVED WITH COURAGE AND HONOR LOL PLEASE ACCEPT OUR DEEPEST CONDOLENCES LOL
I'm an older millennial, and I definitely never heard it used for anything other than "for the win", but if we're talking pre-internet, it's very possible that it was a regional thing. I don't recall ever seeing the acronym pre-internet at all.