The following context comes form Breakfast at Tiffany's page 17. After Mr. Arbuck sent Holly home, but Holly closed the door in his face. Then Arbuck said:
"Hey, baby!" he said, for the door was closing in his face. "Yes, Harry?" "Harry was the other guy. I'm Sid. Sid Arbuck. You like me." "I worship you, Mr. Arbuck. But good night, Mr. Arbuck." Mr. Arbuck stared with disbelief as the door shut firmly. "Hey, baby, let me in, baby. You like me, baby. I'm a liked guy. Didn't I pick up the check, five people, your friends, I never seen them before? Don't that give me the right you should like me? You like me, baby."
My question is why it's "don't' but not 'doesn't' in the bold sentence? As 'that' here represents the fact that Arbuck pick up the check for Holly and her friends.