Because raven Is his mom
Hahaha haha haha haha
Because of several reasons one. He likes Raven two. That is the way he hides his sadness of his life Amin come on! He lost his parents, adopted parents, numerous tragedy's like losing Tera in the original tt
I literally have no idea!
I believe beast boy only calls Raven mama after they kissed. Maybe a term of “my future children’s mother” like how dad calls mum in a family.