I think this sign might be too polite - because y'all are just nasty asses if you can't do this without a sign.
If you are over the age of 7 years old (and I'm being generous here, because you should've mastered the art of pissing in the toilet way before this time) and you still manage to pee on the toilet seat, then you need some fucking home training.
I'm sorry, but I work in a pretty prestigious place. I work at a huge hospital/medical college on the Upper East Side of Manhattan (where not many can afford to even walk around in) with all adults and mostly medical or science professionals (or at least 90% have a college degree). How is it, that with this caliber of brain power and individuals in the population, I can go into the restroom at any given point and 60% (maybe more) of the time there is pee on the toilet seat?
I understand that ladies squat and sometimes the stream might be crazy powerful and spatter about or whatever the hell happens, but why don't you have the common decency to wipe the seat with a piece of tissue? WHY do I have to risk coming in contact with your bodily excretions? HOW OLD ARE WE LADIES?!
Learn some goddamn manners or stay out of my bathroom.