Celie cooking a sober Shug breakfast only to see if she would throw it at the hallway wall.
Harpo telling his father that he was kicked by a mule, when really it was Sophia who punched him dead in the eye.
And of course:
Miss Millie: You wanna come work for me, be my maid?
Sofie: Hell no.
Celie taking the small victory of watching Mister stumble around the kitchen, and then taking off like Road Runner when he tries to light the stove.
Squeak confronting Sofia at Harpo's is classic. After interrupting her dance with Harpo, calling Sofia a heifer, and SLAPPING HER IN THE FACE, Squeak is lucky to merely be knocked into the trapdoor.
The buildup to it is even better. Once the two girls begin verbally sparing, one of the patrons, sensing what's about to happen, quickly calls good night and gets out of here. When the argument starts reaching a boiling point, the musicians quickly pack up and do likewise.
There really shouldn't be any in a musical like this. But Celie's face when she hears her husband referred to as "Albert" is (or should be) priceless.