Robert Irwin is giving fans a peek at what's usually unseen territory: The 21-year-old zookeeper is posing half-clad for an Australian underwear company that's launching its line in the United States.

The saltwater crocodile is a great, stealthy, archaic beast that you wouldn’t expect to pacify with a little friendly tickle on the tail. But here is Daisy, a seven-foot Australian saltie on a grassy ...