Whenever the boys went to a circus, it was generally agreed upon that none of them were to play the games there. As much as they'd deny it, Bruce's sons were highly competitive, most of all with each other. It definitely didn't help that at the carnival games, Dick had insider knowledge on how to win, Damian and Tim have perfected their own techniques on how to dominate at the games, and Jason cheated (which he called evening the odds since Dickface had such a tactical advantage, growing up in a circus and all.)
It was an unspoken rule in the Wayne Household that the boys were never to compete against each other whenever they went to a carnival. It was already a given that they could clean out the prizes on any game. They were Robins, all of them trained to be good in various combat skills, skills that could be adapted to any situation. Winning a prize for knocking down bottles was something they could do blindfolded. They were all highly competitive; none of them liked the bitter taste of defeat. It was good for training, so they could strive to better themselves, but trying to outdo each other, that was the problem.
Damian denied that he was competing with the others. He was just showing how much superior he was compared to his predecessors. The games at carnivals were beneath him, so it only made sense to Damian that he should excel at them.
Tim was a perfectionist. Anything he did, he did well. The games at the carnivals that Dick dragged them to were no exception. He was a natural at them and he had no problem showing his skills.
Dick knew carnival games. He loved playing them growing up, so he figured that his brothers would enjoy them too. He had no idea that it would lead to another competition between them. Tim was talented and Damian was a quick-study. Playing against them (even though Bruce had that no competition rule), was a great non-vigilante bonding experience.
Jason hated carnival games. It didn't matter that he could have escaped his "brothers", the Demon Spawn thought that it was a competition, and Jason Todd did not back down. Especially not from a pretentious ten year-old who didn't know how to have fun without some form of violence or another involved.
Jason knew that he was at a disadvantage when it came to these things. The Brat was driven, he could never stand losing, especially not to any of them. That made him a formidable opponent in anything. Tim was special, and he meant that in a good way. But that also meant that the games were so easy for him. Dickface, well, Dickface knew the ropes from growing up in the circus. It was an unfair advantage that he had over them all.
So whenever they did go to one of these things, Jason did the one thing that he knew he could do better than the others in order to win. He cheated.