Sex Position, when the male lift the female against the wall with her legs wrapped around him and he slams her against it to push him inside her

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.

1. n. A word used in Scrabble that the opponent doesn't see and therefore can not challenge, but when noticed, they get owned.

2. v. To be completely fucked over in the game of Scrabble.

Just another rollercoaster

The most menacing of animals in the sea, if encountered you will have no chance of survival.