Here's the context.
Earlier on in this classic film, three girls go shopping for prom dresses. One of the three, Jessica, tries on a host of options, but settles on the one that "makes [her chest] look good."
Fast forward to the end of the film and we get to see Jessica rocking this bold fuchsia gown with accessories that draw attention to a certain .... ahem..... area.
The moment is only a couple of seconds long, but from across the room her friend, Bella, gestures a compliment along the lines of "If that's what's so important to you, then I'll concede: that dress makes your chest look fantastic."
Thankful that someone noticed the best quality of this dress, Jessica gestures back
"I know, right???"
Between sisters, we use this phrase exactly how Jessica did, accepting of a compliment, but with a little cheeky edge of knowing that the compliment was on it's way.
For example, while we're side-by-side in the bathroom getting ready for the day, Kelsey will be plucking her eyebrows and in that moment, I will say "Sister, you have really great eyebrows."
She'll pause from her plucking and admire her handiwork in the mirror and say
"I know. Right?"
Then we both smile and silently remember Jessica in her fierce fuchsia.
I couldn't find a shorter clip - but here it is.
Just watch between 3:oo and 3:30...
... or you can watch the whole thing.