Facebook CEO Mark Zuckerberg spoke about his grey shirts, which are known to be his fashion staple. However, his explanation about why he commonly appears in public in a grey shirt may sound offensive to feminists.

"I'm in this really lucky position where I get to wake up every day and help serve more than a billion people. And I'd feel I'm not doing my job if I spent any of my energy on things that are silly or frivolous about my life," Zuckerberg explained.

The 30-year-old billionaire seemed to imply that caring about appearance or clothing undermines the ability to work, and the way he described dressing professionally as "silly or frivolous" may be interpreted as a statement against Yahoo! CEO Marissa Mayer, according to New York Magazine.  

Zuckerberg is not the only male CEO known for a distinctive fashion statement. Twitter co-founder and co-creator Jack Dorsey is known for his sharp Prada suit while the late former Apple CEO Steve Jobs was known for his black turtlenecks.

Meanwhile, Zuckerberg and his wife Priscilla Chan were recently spotted in Mountain View, Calif. for the Second Annual Breakthrough Prize Award Ceremony.

Most of the invitees wore black tie to the event but Zuckerberg chose to wear a navy blue tuxedo paired with a blue tie and a less shiny pair of black shoes instead of the patent leather shoes typically worn with a tuxedo, Daily Mail reported.

Zuckerberg paired his tuxedo with a blue tie, which is becoming an alternative to the typical black bowtie at black tie events, according to GQ.

Zuckerberg's outfit at the awards ceremony appeared to be more casual than those of other celebrities who attended including "Mad Men" star Jon Hamm, "Sherlock" actor Benedict Cumberbatch and Channing Tatum's "Jupiter Ascending" co-actor Eddie Redmayne.

On the other hand, Chan donned a sparkling gown also in a dark shade of blue. She also wore low-heeled sandals so that she would not look taller than her husband.

During their wedding in 2012, Zuckerberg also wore navy suit instead of a traditional tuxedo.