When a friend or person of affection
Wraps his/her legs around your own in a flirty manner
While he/she rubbs your legs with their own to turn you on.
In a heterosexual relationship the guy usually begins the leg footsies as an act of cute flirtation.
Erica: "omg Ian and I made out yesterday for like 2 hours it was amazing"
Meaghan: "what the hell!?!?!! How did he manage to get u to do that?"
Erica: "oh! Well i think it was the leg footsies we were playing before" "what a turn on!"
Meaghan: "wow i should try that sometime!"