foot·sie also foot·sy 
(ftsē)
(ftsē)n.
Informal
Idiom: Informal
The act of flirting in which one secretly touches the feet of another with one's own, as under a table.
play footsie
1. To flirt with someone by secretly touching the feet with one's own.
2. To cooperate or curry favor in a sly or devious way.
[From diminutive of FOOT.]