This earned an immediate corner, and when the waterworks and fire siren started (well, fire siren, as I didn't see the fire hydrants being opened), meant his room.
After he calmed down, I went in there and tried to figure out where he'd learned that it was okay to say that. No luck, but I hadn't counted on any.
Asked him if it would make him happy if I called him "You chicken!" in a mean voice (I demonstrated). It did not.
Inquired as to whether he'd thought it would make her happy when he said that. No. Inquired as to whether he thought it would make her sad. Yes. Inquired as to why he wanted to make her sad. No luck.
Went a bit further into the difference between something being funny and something being mean. Demonstrated with a teasing, "Little Fayoumis, you turkey!" giggling and playing with him. Counter-demonstrated with "Little Fayoumis, you turkey!" said angrily. He grasped the difference, and which one was cool and which one was not cool.
Inquired as to whether he liked playing with her. Yes, most of the time. (A fair answer, as I think Angelica's a bit of a brat, but that goes with the age...)
Let him know that him trying to make his friends sad told me that he did not want to play with them, and he was to go back out there and be nice. If he was mean again, he would be showing me that he did not want to play with his friends, and I would ask his friends to go home.
School doesn't put up with that (he's gotten in trouble before, if I recall correctly) and neither will we. We are not about to raise a bully.