you knows it

as far as one knows

To the best of one's knowledge, as far as someone knows or possible information to be gathered about the topic, subject, aspect, or situation.

fuck knows

I don't know; nobody knows; it is unclear.

next thing one knows

suddenly, out of the blue.

the nose knows

Despite the addressee's belief that the speaker was unaware of something, the speaker, in fact, was already aware.