Victory of the Rule Trickster

A and B are playing a game of Sudoku together. They agreed that whoever writes down the answer first wins. The referee places a Sudoku grid in front of them. A has clearly stronger mental calculation ability than B, and A quickly solves the puzzle. B asks A what the answer is, A is too lazy to write it himself, so he tells B the answer and asks B to write it into the Sudoku grid. The answer is correct. The referee is just about to announce A as the winner, but B says one sentence to the referee, and eventually the referee announces B as the winner. Next, they start playing a bean bag tossing game. They agreed that during the game, they must stand in place and cannot move their feet, and throw the bean bag at each other; whoever hits the opponent with their bean bag first wins. A throws the bean bag at B, B dodges sideways while staying in place. B throws the bean bag at A, A catches it with his hand. B says one sentence to the referee, and eventually the referee announces B as the winner. They then continue to the next round of bean bag tossing. But the result is still B winning. A is very upset. From then on, A never plays games with B again.