What do the night riders do to Sam Tatum in Roll of Thunder, Hear My Cry?

From the text:

“Tarred and feathered him!” T.J. announced hastily. “Poured the blackest tar they could find all over him, then plastered him with chicken feathers.” T.J. laughed.

“Can you imagine that?” “But why?” asked Little Man, forgetting our ploy. This time T.J. did not slow down. “I dunno if y’all’s little ears should hear this, but it seems he called Mr. Jim Lee Barnett a liar—he’s the man who runs the Mercantile down in Strawberry. Mr. Tatum’s s’pose to done told him that he ain’t ordered up all them things Mr. Barnett done charged him for. Mr. Barnett said he had all them things Mr. Tatum ordered writ down and when Mr. Tatum asked to see that list of his, Mr. Barnett says, ‘You callin’ me a liar, boy?’ And Mr. Tatum says, ‘Yessuh, I guess I is!’ That done it!”