to talk something over with someone =與某人商議某事
I have got something to talk over with you.=我有事要跟你商量。
to talk over a person's head=說得使對方聽不懂
If you talk something over, you discuss a thoroughly and honestly.
He always talked things over with his friends.
We should go somewhere quiet, and talk it over.
Talk over problems, don't bottle them up inside.
以上例句及說明取自《新世紀英漢辭典》及Collins Cobuild English Dictionary for Advanced Learners
(1)Let's talk it over .
(2)Let's talk over lunch.
(3)Let's talk it over when having lunch.
(4)Let's talk over at lunch.
2015-07-18 11:25:18 補充：
If you talk something over, you discuss it thoroughly and honestly.