Cosecant

Everyone knows sine and cosine. They're the popular kids. Even tangent gets invited to parties. But cosecant? It's just trying too hard.

It's literally just 1/sin. Why does it need its own name? It's a reciprocal with an ego problem. "Ooh, look at me, I'm the hypotenuse over the opposite side." Nobody cares.

And the abbreviation? csc. It sounds like a hiss. It's unpleasant to say and unpleasant to calculate. Just flip sine and move on with your life.