If you had to guess the personality traits that defined Donald Trump’s longtime golf caddie, would things like mild-mannered, reasonable, or housebroken be on the list? Of course they wouldn’t. We’re talking about a guy who prizes loyalty above all else, who flies off the handle at the slightest provocation—real or imagined—and who surrounds himself with criminals, slumlords, massage parlor enthusiasts, and at least one guy who’s said he would do “anything” for him, including kill a man. So, really, this all checks out:

A.J. (who asked that I not use his last name in my book) is so loyal that if someone criticizes Trump, he’ll fight him—and has. One day, when the 2017 Senior PGA Championship was being held at Trump Washington, he overhead one of the Tour pro’s caddies—Brian “Sully” Sullivan—dissing Trump.

“He was running his mouth, sir,” says A.J., who calls everybody “sir” or “ma’am.” “Yellin’ about Mr. Trump. He was sayin’ to somebody, ‘Don’t tell me how I have to feel about him! I hate that motherf-----!’”

A.J. says he came up on Sully from behind and put him in a full military choke hold, yelling, “Now, you listen to me, f-----! You’re not gonna come to Mr. Trump’s course and eat Mr. Trump’s food and then use the word ‘hate’ about my president. I won’t have it, you got me?”

A.J.’s intolerance for people running their mouths about the president is not confined to fellow caddies. Here’s another fun story he told sportswriter Rick Reilly, for the forthcoming book, Commander-in-Cheat: How Golf Explains Trump, about having to deal with people disrespecting his man:

Tensions were high because, for seniors, it was a big tournament and Trump’s name was attached to it. There were protesters by the entrance every day that week, and A.J. always made sure to drive his car right by them. “There’d be a bunch a women out front with all their stupid signs, sir. So I go real slow by ’em, see, hit the window button—zzzzzzttt—toss ’em the bird and I yell, ‘F--- you!’ They’d start yelling at me and I’m like—zzzztttt—right back up. And I laughed, sir.”

If loving Trump so much that he has to tell people to go f--k themselves and/or assault them to set them straight is wrong, well, sorry. A.J. doesn’t want to be right.