You know your...

You use 'you know your...' to let your speaker know you're about to say something funny. By using 'you know,' you are also trying to get the speaker into your corner, so they will relate to you.

Example:
-You know your cell reception is bad when you get a text message 5 hours later!
-Yeah, that's pretty bad!

I know, right?!

'I know, right?!' is an expression used by Americans to show the other speaker they hear or understand what the other person is saying or means, and agrees with them.

Example:
-Your total is $3.00.
-$3.00 exactly?
-I know, right?!