Bruce Jenners kids have his back. The former Olympian, who is quietly undergoing a gender transition from male to female, was the target of iHeartRadio Music Awards host Jamie Foxx’s opening monologue, and his eldest son Burt Jenner isn’t laughing.

After Foxx joked that Bruce will be performing a “his-and-her duet all by himself” while opening the awards show on Sunday night, TMZ caught Burt at the airport on Monday, March 30, and the 36-year-old (whose mother is Chrystie Jenner, Bruce’s first wife) defended his dad.

“I think he is just copying Kevin Hart because Kevin Hart is taking all his movie opportunities. He’s copying him — man’s on a roll and Jamie Foxx is on the way down. [Hart’s] got his mojo going so he’s got to copy what’s working,” Burt said of Hart, who reportedly poked fun at Bruce during Justin Bieber’s Comedy Central roast.

“[Hart] did it in front of my sister [Kendall Jenner]— he got lucky. He can make jokes about my dad all he wants but he can’t make jokes in front of my sister and make my sister feel awkward.” Had Burt been at the event? "I would have charged the stage,” he predicted. “If security got to me beforehand, I would’ve thrown something at him.”

After Foxx made the insensitive joke, which felt particularly off-base at the music-focused event, viewers accused Katie Holmes’ secret boyfriend of transphobia

“That Bruce Jenner joke wasn't funny at all. Like what was the point of that?” one viewer tweeted, while Perez Hilton added: “Boo! Shame on you #iHeartAwards for allowing @iamjamiefoxx to be transphobic on national television! Those #BruceJenner jokes were wrong!!!”