idunnoes
When a socially inept person, typically a blonde, is presented with a question they don't know the answer to, they try to recover by trying to look sweet, yet confused, and smile while twirling hair around they're finger and simply answer "idunnoes"
Mike: Hey Shannon! Do you want fries with that shake? *wink wink*

Shannon : *twirling her hair extensions around her finger* "idunnoes"