Knowing How Start Ends

Boy: how does start end?
Girl: good question
B: i know
G: why ask?
B: you're right
G: i know
B: oh do you now?
G: i think so
B: yes, if you know now
G: i didn't know that
B: well you should have known
G: i thought i did
B: i thought so
G: wow!
B: i know