The simple reason to use "öpö" with purpose is because lol just plainly sucks.
Used when joking about serious topics. Also used when there's an inside joke.
Usually at the end of a sentence that means no harm.
Can be used as an expression. Such as when one uses smiley faces.
Not to be taken seriously.
Person 1: "That's pretty obvious."
Person 2: "Your mom is obvious. OpO"
Guy: "That's one thing I don't like about you. You're tan."
Girl: "Is that a bad thing?"
Guy: "Yes. It means you've been out of the kitchen too much. OpO."
When it's used by purpose (and it's not a misspelling), I think it should mean "lol".
I use it in the meaning of "Oh, my god...".
<User1> 1 DESTR0Y Y0U 4LL