When intense female ejaculation is initiated by deep anal stimulation during intercourse. This is commonplace with a specific group of women - see "squirters." However, in this case it is specific to anal stimulation only. The roots of this word are drawn from the distinctive scent produced from the excreted fluid.
Last night I was balls deep in my girlfriend's anus and she fishmilked all over my chest and face.
by Kevstew January 02, 2009