a client referred to me as that 'spanish looking teenage girl'

i don't know any dominican-specific racial slurs, but you can always add some kick to a slur by mixing up the race in question with a vaguely-related racial entity, like calling someone Japanese "Chino".
 
a permutation of "beaner" or "bean-eater", commonly an anti-mexican slur, but possibly also applicable to the rice-and-bean-eating peoples of central america and the Caribbean
 
okay guys 2 things

a) I found out on sunday that I'm part croatian

b) I really resent that my fine spanish heritage is being dragged through the mud in this thread by being compared to :shudder: the domincans