What's "footsie"? I've never heard of this word. Do you use it often?

Native speaker’s answer
Rebecca
"Footsie" is used in certain contexts! It's the action of touching someone's feet lightly with your own feet, usually under a table. It shows a kind of romantic interest. Here it's used to be funny since we know there's no romantic interest between Patrick and SpongeBob. Ex: When we first met, we would play footsie under the table for hours. Ex: Stop playing footsie with me, Peter.