"I promise not to fuck your bike," says Alice.

He does not promise not to go home later and think about fucking it. Mmmmmm.

(Promising something doesn't mean the same thing to him that it does to most people. The promise, by itself, is meaningless. What he's saying, the thought behind the words, is that he acknowledges she doesn't want him to do that and therefore predicts that he won't. He isn't paying much attention to this definition at the moment, but it's still there.)

"And I am glad that you are keeping it, because it's fucking awesome and so are you."