The phenomenon of female ejaculation is at best, poorly understood, and at worst, dismissed entirely. The latest research I'm aware of was in New Scientist and was far from conclusive, but stated that while female ejaculate is thought to originate from the bladder, it contains no urea and therefore is not piss. This is consistent with my own close quarter observations of a colourless, odourless and tasteless watery fluid which dries completely leaving no stain on the bedding - unlike urine. Furthermore, it doesn't seem to stream out of the urethra, rather it appears to come in a 'flood' of no discernable point origin. Admittedly, reliable observations are rather difficult at this stage due to inherent vaginal untidiness and the propensity of its owner to thrash about like an epileptic at a Hawkwind gig, but next time I'll ensure I don my headtorch first and collect some samples.
However, 'squirting', as depicted in pornography, is usually just urination masquerading as ejaculation for erotic effect (especially when it shoots across the room).
Besides, I couldn't really give a fuck what it is because, as Sadie says, either way it's a hell of a compliment to one's tongue technique.
