The act of ejaculating an excessive amount of semen into a womans vagina while shes laid down, spaying whipped cream on top, setting up your face directly in front of it, and having your friend give her a good ol' Macho Man Elbow Drop™ off of the bed

Briefly, "the realization that each random passerby is living a life as vivid and complex as your own." Originally from the Dictionary of Obscure Sorrows, which has a lot more beautiful neologism definitions like this you might enjoy.