To "play footsie" is an idiomatic expression that refers to a form of flirtatious or secretive physical interaction between two people, often under a table or in a situation where others may not easily see it. In this action, one person uses their feet to touch or gently rub the feet of another person. It can be a subtle and often flirtatious way of expressing romantic or sexual interest.
It's important to note that "playing footsie" can vary in its level of intimacy, and it may be considered inappropriate in certain settings or situations, such as during formal meetings or in professional environments. It's generally an informal and often light-hearted way of showing affection or interest in a playful manner.