When a woman milkstamps someone by accident. That is, a milkstamp without the conscious intent of the woman giving the milkstamp.
If the milkstampee puts themselves into a situation where they are likely to receive a milkstamp and the milkstamper in question was not trying to give a milkstamp, it is still considered a spilled milkstamp. Even if the milkstamper enjoys the spilled milkstamp afterwords.
"She gave me a sloppy 1/2 and 1/2 spilled milkstamp."