frolic, play, amuse, play with
耍 centers on lighthearted, playful activity: frolicking, amusing oneself, or playing with something in a carefree way.
耍 combines 而 (originally a beard or whiskers, later used phonetically) with 女 (woman), suggesting playful or frolicking behavior. The exact historical development is uncertain.
A woman (女) with a beard (而) is playing around and frolicking, amusing everyone.
For サ, imagine a playful woman saying 'Sa!' as she jumps into a frolic: Sa -> サ.