1. to insert the male member (penis) into the mouth in order to derive sexual pleasure.
2. the sucking or licking of the female genitalia (vagina) in order to derive sexual plaesure

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.