Goldilocks Theorem is a technique for guessing answers to multiple choice questions. You throw out the highest and lowest answers and guess from what's left. Typically applied to three and four answer questions.

When the bed is either too soft or too hard, and you have a horrible night sleep

A women's box that isn't too loose or too tight, it's just right.

The breasts of a woman that are not too small, but not too large. They are just right. They dont get in the way, but are still visible. They work on almost any woman and is the icing on the cake for a girl who one would consider cute but not hot.

The immensely satisfying poop that comes after waiting just the right amount of time.

Any planet that's (hypothetically-speaking), not too hot, or too cold and can support CHZs: 'continously habitable zones' and have a large Drake number: the possibility of the existant number of intelligent galaxies in the universe put into an equation.

When you feel just right!

(From the Goldilock and the three bears story)