what's in a dog's name?

[mike thomas]

Doth not Rosemarie and Romeo begin both with a letter?
Rom. I Nurse, what of that? Both with an R
Nur. A mocker that's the dogs name. R. is for the no,
I know it begins with some other letter, and she hath the
prettiest sententious of it, of you and Rosemary, that it
would do you good to heare it

What the...?

Is the nurse mad or what?

ideas anyone?