2007 (UTC) 
 ::Yes, it's likely quite rare but it's going to be a lot more common then sitting on the toilet seat. Firstly, if a male masturbates and ends up deposting semen on the toiler seat, we can presume he's likely to clean up after himself. If he doesn't the woman is likely to clean it up anyway. Some sperm may still be lef this amount is going to be minute, far far smaller then the drips that could easily come into contact with the vulva by accident during mutual masturbation. Secondly, I would presume most woman are liable to be sitting with their vulva hanging over the hole rather then touching the toilet seat. Therefore it's rather unlikely any sperm that is on the toilet seat would come near the vulva anyway. If a woman is urinating, she's may also wash away any semen that comes near the vulva and she's likely to wipe any that does remain away after finishing. Even if any does remain, it seems unlikely it will enter the vagina. On the other hand, during mutual masturbation semen (and therefore sperm) may end up near the vulva or on the hand of the male partner. This could easily be visible drips and this could easily be deposited into the vagina during the course of masturbation. Futhermore, as the woman is in a state of arousal and may have an orgasm, her bodies also likely to be more conducive to this sort of 'accidental insemination'.  16:42, 7 June