だお (net slang?) I think I remember some characters in steins;gate ending sentences with or . What does it mean?

I'm pretty sure that it came from ``.

This is just my opinion but by using `` instead of `` for a character, you can make him/her sound like a person who is cute, laid back, easy-going, girly, ..., etc.

I think that these characters often don't speak clearly or speak like a little boy/girl just to create the characteristics listed above so `y` is dropped in `dayo` and it sounds like `dao`.