He’s always up for a challenge, and Orlando Bloom had to strip down to his birthday suit for his new flick “Zulu.”

During his interview on “Watch What Happens Live,” the “Pirates of the Caribbean” stud talked about maintaining his modesty thanks to a “c**k sock.”

Of his willingness to get nakers, Orly noted, “You’re in luck ’cause earlier this year I spent about seven days on set wearing just a c**k sock because I’m nude! It’s a film called Zulu.”

“It stars myself and Forest Whitaker. It’s directed by this fantastic French director called Jerome Salle. We premiered it at Cannes. You do get to see the full Orlando Bloom.”