The context of the following conversation is Ash pushed the boy into the pool for what he thought was a harmless practical joke.:
Ash says I'm sorry, I wouldn't have pushed him in the pool if I knew he couldn't swim!.
The friend responds Why did he push him in anyway?.
Ash responds We were all joking around, everyone was pushing everyone in, it was just a harmless prank.
The friend responds It isn't harmless when that boy didn't know how to swim.
Ash responds No one knew that, why was he at the pool if he didn't know how to swim?.
The friend responds Now that is a good question!.