From Swimming; Acronym for: Get In Shut The Fuck Up And Swim. A term used to describe a long swimming workout or a specific long challenging swimming set with few breaks or rest periods. May also be used to describe a training set given by a coach to deal with athletes who are slow to begin their warm up.

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.