“Fa2” means “fatoe”, which is Dutch slang for “joke”.
The interpretation is derived from mistaking “fa2” for “fa” multiplied by 2, so “fafa”.
“Fafa” is adopted by a very small group to have the same definition as “fatoe”
1: Dion: “That was a little fafa.”
Patek: “Ah, good one.”
2: Nicky: “Hahaha what a fafa”
Flip: “fafa?! What does that mean”
Nicky: “ Fa2; fafa right?”
Flip: “No, fa2 means fatoe hahah”