you never know

Definition of you never know in English English dictionary: Used to speculate about a slight possibility
They are only running times in the 13.20s, but next year he could run 13.25 and you never know, he may end up running 13.1 quite easily.
you never know what you've got till it's gone: Good friends and acquaintances shouldn't be taken for granted
you know: Expression signifying a pause or hesitation
I don’t usually get nervous in games and, you know, taking free kicks and penalties but that’s the first time I’ve been that nervous in, in a game, where I have to, I’m in a situation where I’m, you know... - BBC Interview with David Beckham.
you know: Expression used to imply meaning, rather than say it, such as when a person is embarrassed to say a word
Person 1: I heard you want to do that thing with me. Person 2: Do what? Person 1: You know... umm... Person 2: Oh do you mean sex? Person 1: Yeah.. that..
you know: Implying something generally known or known by the listener; used as a gap-filler in conversation
you can never know: one never knows what the future holds him, life certainly holds a lot of surprises
you know: it's obvious that you know, you're already aware of
you know: (Informal) used in speech instead of a pause, symbolizes a comma or period (Example: "She left, you know, and then she...")