Recently there has been a semantic shift in the pornographic word 'cum.' Traditionally, the word, as a noun, is used to designate semen. However,'cum' is now used to designate also female fluids during sexual activity. The concept of 'female cum' is discussed in relation to examples from a corpus of two hundred erotic short stories collected from the Internet, and to the physiological realities of female fluids during sex. In order to show how the innovation of 'female cum' is useful in written erotic narrative, a comparison is made with filmed pornography and drawn erotic comics. Finally, I argue that 'cum' in this new context is used as a device to arouse sexual excitement.