Different webboards say it's for real and folks know him as a practical joker. Hope he didn't joke himself out of a job. (I also read it was his last day working at that airline, and that would make the most sense.)
That said, uniform regs are uniform regs whether you like it or not. You know them AND the (crappy) salary you'll be earning before you sign on the dotted line, so there is no excuse really for immature and unprofessional behavior such as this.
What really grinds my gears is some of you who say it's hilarious would come down HARD on a FA for doing something similar and calling out their unprofessionalism and disrespect to their employer and fellow crew members. Gotta love double standards and hypocrisy.