I'm still a young umpire. I was working a 15U game.
I called B1 out on strikes. The pitch was most certainly a strike. It's the protoypical pitch where the kid ducks, and the breaking ball breaks right over the top for a strike. B1 proceeds to then say "Are you [bleeping] kidding me?" in response to the call; not very loudly. I did not eject him then.
I proceeded to walk towards the opposing dugout to retrieve some new baseballs. I saw him then throw the bat in the direction of the dugout. At this point, I proceeded to eject the player.
Then, the coach of the ejected player's team comes over and asks me what he said. He seems to be calm with the explanation in which he was given. The assistant coach gets involved, and starts screaming, "What did he say?" ... And I proceed with, "I'm not going to repeat it, and I have informed the head coach, and should he choose to tell you, that is his prerogative" ... And he continues to repeat himself in a derogatory manner, to the point in which I tell him that if he continues this conversation that he will be ejected, and he stated "I just want to know what he said!" ... I ejected him, as well.