muvva is the slang term for mother. It looks better than mutha. It's the perfect substitute for mother in any context.
ya muvvafooking retard!
ya muvva is fat.
welsh derogatory term for a persons mother meant as an insult which usually follows a question.
1st man: wosapnin bruv
2nd man: your muvva, thats wosapnin innit bruv!