Alibaba CEO Jack Ma attended a mass wedding for his employees on Friday.

At the wedding, Ma made a pun on China's infamously gruelling "996" work week which he advocates.

Ma told the employees that while in work they should adhere to 996, in life they should follow "669," which he described as: "Six days, six times, with duration being the key."

Visit Business Insider's homepage for more stories.

Chinese billionaire and Alibaba owner, Jack Ma, attended a company mass "wedding" on Friday, telling employees they should be having lots of sex to mirror the exacting work weeks demanded by the firm.

The "wedding" was a celebration of all the Alibaba couples who got married over the previous year, and is a regular fixture on "Ali Day," an annual event honoring the company held every May 10.

Ma recently defended the infamous "996" work week, which Chinese tech workers have protested against. 996 means 9 a.m. to 9 p.m., six days a week, and last month the billionaire called it a "huge blessing" for young workers.

Read more: Chinese tech billionaire Jack Ma says it's a "blessing" for his staff to work gruelling 12-hour shifts, 6 days a week

Ma made a pun on the controversial working practice on Friday, telling the 102 couples present: "At work, we emphasize the spirit of 996. In life, we should follow 669," as per the Daily Mail's translation.

"What is 669? Six days, six times, with duration being the key," said Ma. In Chinese, the word for "long" sounds like the word for "nine." The Mail also reported that the quote was released on Alibaba's Weibo page accompanied by a winking emoji.

The speech drew criticism online, with some saying the comment was lewd. "996 during the day, 669 during the night, I guess after less than a month I might have to stay in the ICU forever," read one comment from a Weibo user, as spotted by Technode.

Ma also encouraged the couples present to have children. "The first KPI of marriage is to have results. There must be products. What is the product? Have children," Ma said.