For Cheating:
There nothing wrong when Yamamoto thinks that Gokudera is cheating.
But there is something DEFINITELY wrong when its Gokudera who is thinking that.
So, he grabs the baseball freak by his hair, and pulling very hard, he says in a bitter tone.
-WHAT THE FUCK YOU DID?
Yamamoto seems surprised for a moment, so then, he realizes what is really happen, with a smile, that's looks feral, he looks at Gokudera, and says in a cynical voice.
-YOU started. Let's play a fair game next time…