dear ladies of the 6th floor,

Clearly you have very. important. things. to discuss.
So important that you can't wait to have your conversation somewhere more appropriate than the woman's 6th floor bathroom. Now while you may not see a problem with having a full-fledged discussion through stall walls, while one of you relieves herself, it is a little weird for the rest of us on the floor who also need to use this bathroom. Also weird when you start talking a little louder to talk over the sound of me urinating. My apologies for clearly interrupting you.
Perhaps in the future, you could halt your discussion for the three minutes it takes me in the bathroom, then continue talking about very. important. things. when I'm gone.

Thanks and happy urinating,