Much like a graffiti tag, a computer hacker's calling card is of utmost importance. It should signify bold recklessness with an utter disdain for rules, borders, and authority. This badge of honor will serve as a warning, left behind in the wake of infected systems and mainframes: Don't try to quell my wrath, for I am a ruthless vigilante, a spectre in the online realm.

Or you could write a program that shows a picture of Rick Astley on people's iPhones and just hope for the best.

Hailing from Wollogong, Australia, 21-year-old unemployed programmer Ashley Towns developed a self-replicating program -- or a "worm" -- to infect jailbroken iPhones and features a reference to a three-year-old joke that even your mother finds lame. Known as Ikee, the worm only targets users who have unlocked their iPhones in order to run unauthorized programs.

Once infected, the iPhone displays a portrait of '80s music icon Rick Astley -- famous for his falsetto single "Never Gonna Give You Up" and countless misdirected YouTube (GOOG) videos. The threat pretty much ends there, though the worm could be modified to mine sensitive data and cause more damage -- similar to one designed by a Dutch hacker who demanded a fee from the victims to fix the problem.

Towns hadn't intended for the malware to become as widespread as it has -- though it's still largely confined to Australia. He admitted to IDG Connect, "It was supposed to be a small prank. I definitely wasn't expecting it to get as far as it did."

Towns also revealed that, given the overall innocuousness of the worm, he's been thanked by users for reminding them to change their default iPhone passwords -- one of the key exploits in the program.

Apple (AAPL) has yet to release a response to the attack -- either because only jailbroken iPhones are vulnerable (a definite bonus for Apple) or the company is incredibly embarrassed for the hacker's banality.