* Dwayne "The Rock" Johnson: His birthday is May 2, 1972.
* Chris Cornell (singer of Soundgarden): While he is not widely known as "Rock," he did have a band named Soundgarden and many fans referred to him as "Rock." His birthday was July 20, 1964.
* "Rock" could be a nickname for a specific person.
Could you please give me more context? For example:
* Who are you referring to?
* What's the context of the question?
This will help me understand who you mean and give you the correct birthday.