SHAPES expressions

fit a square peg in a round hole = to do the impossible

to square that circle = to do the impossible 

to be square

to come full circle

circle jerk

The term square meal is a nautical term from the days of old sailing ships. Any significant meals (usually the last one of the day) would be eaten off a square-shaped wooden plate, which also served as the tray. A decent meal on board became known as a square meal.

le da mil vueltas

he runs circules around (another person)

how do you square that circle?  

triangulate

the pentagon