I can be completely asleep and hold conversations with people, then when I awake my speech is slurred and I'm groggy with little to no memory of the conversation.
I still think I'm a bit strange.
Don't worry you're not alone with this talent, almost everyone in my immediate family does this. There have been phone conversations with my mother that she can never remember.
I only know of one time that I've talked in my sleep. I all of a sudden woke up and there was a person in front of me, who thought I was awake.
Another thing, I can do all different kinds of whistles, even the hum and whistle thing. So far I've counted 5 different types of whistles that I can do, three of them were different finger whistles. can even moderate how loud they are when I want to.