President Herbert Hoover knew how to speak Mandarin Chinese, along with his wife Lou Henry Hoover. The Hoovers learned Chinese when they traveled to China in 1899 and Herbert Hoover worked there as a mining engineer to the Chinese emperor with the consulting group Bewick, Moreing and Co.
While in China, the Hoovers got caught up in the Boxer Rebellion, which was when Chinese nationalists rebelled against the colonial control of their nation.
Occasionally, Herbert and Lou Hoover would speak Chinese in the White House so they could talk about private affairs without anyone understanding them.
Unlike another first lady, Jackie Kennedy, Mrs. Hover never “cut an ad” in a non-english language. Mrs. Kennedy is still remembered for this spot, where she pitched her husband John Kenney’s campaign in her somewhat accented but still quite flawless Spanish.