meaning You know what I mean, or in response to a questions, Yes, I understand - or can be said in agreeance, like a second to the notion.
Kristen: Dude, that bitch is nasty - Yadidaidig?
you can also put your hands together and rub them together before you say yadiddddiaaa DIGG? or roll your tounge like mac dre. yarrrrrrrrirrrrrrra holla?
hey man we thizzin' yaddidiie?
yeah for sho yaddida meann