A: I have a surprise for you, Do you want to know what my surprise is?
A: Your favorite team won the game
Is the usage of my correct? or we must say:
Do you want to know what the surprise is?
It can be both my surprise (because I have it) and your surprise (because it is for you).
But certainly also the surprise, today's surprise.
If you specifying that " 'I' have surprise for you." then you don't need to specify "MY surprise". You can just say " Do you want to know?"