When e-cigarette market leader Juul removed its popular sweet flavors such as mango and creme from stores last year, co-founder Adam Bowen said publicly the company was willing to take a cut in sales to "do the right thing and prevent underage use."

The conversation at Juul's San Francisco headquarters, though, was far different.

"You need to have an IQ of 5 to know that when customers don't find mango they buy mint," then CEO Kevin Burns told employees, former senior vice president of finance Siddharth Breja alleges in a wrongful termination lawsuit against the company filed Tuesday.

The company allegedly had research from consulting firm McKinsey & Co. that showed customers would purchase mint instead. And that's exactly what happened, according to Breja, who was fired in March. Sales of mint pods surged after the sweet flavors were removed from stores. Mint pods accounted for about two-thirds of Juul's total pod sales in February 2019, up from about a third the previous September, the lawsuit alleges.

The lawsuit documents a culture of intimidation at Juul, which was formed in 2015 and quickly grew into a market leader, accounting for about half of the industry's market share this year. Breja, who claims he was fired in retaliation for sounding alarms at Juul, says the company knowingly sold at least 1 million contaminated mint-flavored pods and refused to recall them.

Breja alleges that Burns took a "win-at-all costs" approach to running Juul, telling employees who challenged him that there could "only be one king at Juul," and that "king" was him. Burns allegedly once told Breja and other executives to "tell that motherf----- that I'll take him out of the room and shoot him with a shotgun if he challenges my decisions."