Tony laughs and torments because it's the only sane way he knew to react to this. He knew that it was a bad idea to let McGee cover the backdoor on his own, and he was proven right when that vicious dog attacked McGee. He still could hear the barking and biting in his head and his gut clenched when he remembered McGee's screams. Lying there, that dog on top of him. He freezes for a few seconds before he is able to react. This isn't suppose to happen, McGee isn't suppose to get hurt.
Tony can handle it when he is hurt, but he hates it when some one else is hurt, because he can't do anything else than sit on the sidelines, there is nothing to do for him. So he prefers himself getting hurt, it almost seems easier that way.
Now, Timmy is safe. Not McGee, Timmy. Medics checked him over and he was just fine, a couple of bandages and he was as good as new. Except for the fact that he wasn't.
His shirt was stained with blood and there were bandages on his neck and arm. But the worst part of all was the look on his face. It was as if he was looking at a wounded teddy bear. And if Tony was honest he wanted to drag McGee home with him, undress him, tuck him in too their bed and nurse him back to health with kisses and chocolate. But the look on Gibbs' face had told him that that wasn't going to happen.
Gibbs knew, Gibbs always knew what was going on with his team. And right now he told Tony to suck it up and act like a man. So Tony teased Tim, making fun of him, this way he wouldn't have to see the look on McGee's face. So he wouldn't feel the urge to pick him up and kiss it all better.