To flirt with, especially in secret.调情：调情，尤指偷偷地To cooperate or curry favor with in a sly or devious way.搞秘密交易：以一种秘密的或不正当的途径合作或搞交易
柯林斯高阶英汉双解学习词典释义
PHRASE
(在桌下)脚碰脚调情，用脚挑逗
If someone plays footsiewith you, they touch your feet with their own feet, for example under a table, often as a playful way of expressing their romantic or sexual feelings towards you.