An event in which somebody nearby had a camera phone, captured a unique and most often embarrassing moment and then promptly uploaded it to their Facebook profile.
Example: Your best friend passed out at a party, so everyone decided to draw pictures on his face and wrap him in saran wrap. Being the good friend that you are, you captured that Facebook Moment by snapping a photo of him on your camera phone and then posted it on your Facebook profile long before your friend woke up.
Moments that are so insanely random, retarded, original, stupid that they are epic.
Therefore, making them Facebook material.
A moment in life or on webcam that something funny or interesting happens to a friend or lover that you feel all your facebook friends NEED to know. (ie. embarrassing moment, accident, personal matters) That you post on your wall on Facebook
I made a faceplant last week and my bestfriend decided it was a facebook moment. Now people make fun of me for it!
My girlfriend did a booby dance last night. It was a total Facebook moment!