Why did Two-Bit slap Pony hard across the head in Chapter 3 of The Outsiders?
Johnny Cade is the pet of all of the greasers in The Outsiders, in part because of his terrible home life. His parents argue all the time, and he is occasionally beaten by his father. So, it is an unspoken rule among the boys never to mention the bad times Johnny experiences at home. When Ponyboy becomes frustrated with Cherry's questions about his own relationship with Darry, he lashes out at Johnny:
"An' you can shut your trap, Johnny Cade, 'cause we all know you ain't wanted at home, either. And you can't blame them." (Chapter 3)
Tow-Bit ses that Johnny's reaction is "as though I'd belted him," so he retaliates with a "good one across the side of the head." Pony recognizes his mistake, and he apologizes to Johnny.