The desire to have sex.

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.

a hand-to-hand position, resembling a high-five, done as a warm-up exercise, in general, before some kind of physical activity, or sport. So called, because it reminds one of the famous Glenn Miller instrumental, of the title. A locker room dance, prior to a football game, or even prior to football practice, using hand-to-hand combat techniques, may be called "In The Mood."