What does “I know, right?” mean?
Is the expression "I know right" grammatically correct? I hear it a lot and I think I understand what it means, but it just sounds wrong to me.
I think what you're referring to is usually spelled:
There are two parts here. The first, I know, is an ordinary declarative sentence, indicating that the speaker agrees with or supports the other person's assertion. The following right is a kind of conversational invitation to agreement. When you end a sentence with right (using rising question intonation), it indicates that you expect the person you're talking with to confirm your statement:
This usage of right as a kind of tag-question is colloquial, but not grammatically incorrect. It can be freely used in speech, but should usually be avoided in writing.