Cyd's first name is short for Cydavia.
Paulie: You scared the crap out of me.
Tony: I used up a couple of Huggies myself.
Tony: Cyd? That's your real name?
Cyd: Yeah, Cyd with a C. It's short for Cydavia. But if you ever call me that I will shoot you.
Tony: Don't shoot
Cyd: Shoot you? Why would I shoot you? You're a cop...and I'm a cop.
Tony: You're a what?