"How do you know I haven't--"

--said it before? It's obvious that's where he was going, his usual trolling smirk in place. But he glances down and meets those big eyes staring up at him over the cow's snout, in her mouth. And he remembers McCoy's warning in the hallway, the way he hadn't cursed in front of the kid.

And his expression softens and he doesn't say another word.

That's right.

Jim Kirk just willingly curtailed his smart mouth.