Robert Irwin freaks out US stars Jimmy Fallon and Kevin Hart

Robert Irwin has made his funniest appearance yet on The Tonight Show starring Jimmy Fallon, terrifying actor Kevin Hart with a series of animals.

The 14-year-old son of the late Steve Irwin traumatised Hart, who is afraid of animals, with a king snake, a tarantula, a baby ostrich and a falcon during a guest appearance on the US talk show yesterday.

Hart could barely sit still as Irwin began with a two-month-old ostrich Giselle, prompting Hart to run across the stage saying, "You can kiss my ass, no. What is that noise? You know what she's saying? I want some little black man."

Irwin then introduced two king snakes named Lebron and Elvis, which Hart refused to hold.

"I'll fight you man. I promise you I'm going to swing on you," he said.

"My ass is sweating. I got so much sweat dripping down my ass right now. I'm so nervous.

"This is how black people die in horror movies."

But it was a tarantula named Big Red that left Hart and Fallon crying with laughter.

With the spider sitting on Fallon's hand Irwin revealed it was only human breath that would spook it.

Hart began leaning in and yelling "Jimmy" in an attempt to spook it, as Fallon pleaded with Irwin to take it.

"That was the scariest thing I've ever done," Fallon said as Hart hunched over in fits of laughter.

The segment ended with a falcon which flew across from the audience to the arms of a terrified Fallon and Hart.

On Instagram Hart described it as "the funniest thing that I have ever been a part of".

Irwin, who appears regularly on the show, was promoting their new reality series Crikey! It's the Irwins on the Animal Planet channel.

Watch the hilarious segment below: