What word does your mother always say?
Spanish costa "coast," from same Latin source as English coast (n.). Used in Britain from 1960s in jocular formations (costa geriatrica, costa del crime, etc.) in imitation of the names of Spanish tourist destinations.
costa cos·ta (kŏs'tə)
n. pl. cos·tae (-tē)
A rodlike internal supporting organelle that runs along the base of the undulating membrane of certain flagellate parasites. Also called basal rod.