A moment where you get into deep conversation with someone (often times someone you haven't talked to in a while, like an old best friend, ex boyfriend/girlfriend, or maybe even a best friend who you need to talk to), and you talk about life, and what has been going on. Often times there are long silences and it feels like there should be a song playing in the background.
Also known as a Hills Moment.
An example of this is when someone meets up with an old friend they haven't talked to in a while (perhaps at a coffee joint or a restaurant, or even at their apartment) and they meet up and talk about things and maybe even talk about being friends again, that's a Laguna Beach moment.
"Yeah, we met up and it was totally a Laguna Beach moment."