laugh in one's sleeve

— Nixon boastfully called the seven days he spent on the Chinese mainland "the week that changed the world"–without, however, specifying whether the change was for the better or for the worse. The way he humbled himself before Mao Tse-tung and Chou En-lai reminded me of the tribute-bearing foreign emissaries of the previous centuries who went to Peking to pay homage at the Chinese Imperial Court. Nixon's hosts must have laughed in their sleeves at his behavior during their meetings.