Requiem for a Dream : "Know what I like about paddy chicks?"

(English is not my first language)

So, according to the subtitles, Big Tim says this to Marion.

Urban Dictionary tells me that "paddy" is a term for an Irish person.

Is he implying that Marion was from Irish descent?

Sort of. It's also a deragotory term for white girls. I think he was using it more in that way.