Brunette with the magic panties!

At her day job as a waitress, Andrea has recently made an interesting discovery. Like waitresses everywhere, she has a certain favorite outfit that she always wears to work, because it seems to work the best for making tips. She's not wearing that outfit here, but she is wearing the underwear, and they don't last long before they are off and her perfect naked body in full view!
Just until last week, Andrea never understood why her tips would double whenever she wore exactly this outfit. Then she tried an experiment. If she wore the same tiny little skirt, and a different pair of plain white panties, her tips returned to normal. One day, she tried with no panties at all, and that day her tips were pretty damn good! She met a guy that day on the job and had an excellent time on her lunch-hour. But in the end her tips were about the same. Finally she decided that these panties were the real money-makers! Can you see why?