Robert Irwin Grows Up and Fills Out in New Underwear Campaign

When Robert Irwin, the son of the late "Crocodile Hunter" and conservationist Steve Irwin, decided to do a sponsorship for the iconic Australian Bonds underwear brand, the 21-year-old realized one thing: He had to do more sit-ups and cut down on the carbs.

His decision certainly paid off, as pics of the handsome environmentalist show that he fills out the tight-fitting boxer briefs quite nicely. And his athletic upper body had us doing a double-take. Click through the pics in the Instagram above to see how.

Robert Irwin may be saving animals, but it's his animal magnetism that's being exploited here, and we are happy to be ensnared by his thirst-traps.

In one picture Robert is carrying a huge snake. It's wrapped around his shoulders as he stands in nothing but white boxers. Although the large serpent is the intended focal point, we can't help but notice the other protruding mass in the snapshot.

There's another picture in which Robert is lying on the ground and what looks like a spider tattoo on his upper arm. If you zoom in –- we are guessing you're zooming in on the spider –- you'll see it's real.

And in the short film in the Instagram above, a very at-home Irwin relaxes with a drink with the tagline, "Why are Australians so laid back? It's simple, they're all wearing comfy undies." That he is doing so with a snake wrapped around his arm and shoulder while a tarantula crawls up his leg only indicates just how comfortable he is.

Another short film from Bonds shows him behind the scenes wearing Guyfront Boxer (available in the US on Amazon) as he works out before the fashion shoot.

In an interview with People, the young Irwin said he was approached by Bonds about doing the photo spread, and his response was a "pretty immediate yes." Still, despite the sexy photos, he remains modest.

"I wish I could say I was very suave and cool about the whole thing, but I was like, 'Yes! Let's do it!' Because Bonds in Australia is an absolute icon," he explained. "Also, I'm at this point in my life where I'm trying to do as many different and random exciting things, and if it's something that makes me a little bit nervous, that I've never done before, and it's a bit of an adrenaline rush? That's what I want to be doing."

Senior Irwin would be proud that his son is carrying on his legacy. At one time reality television or a good docuseries were the best ways to bring awareness to a cause. Now, it's all about social media and getting attention that way. Robert is definitely turning heads and hearts with this new collab with Bonds, and if one endangered animal can be saved by doing a series of tight underwear selfies, that makes the world a better place.