Mmmm.... It worked.
[7] Sell arousal-stained pink dragon-scale print thong (Stained)
I'm not sure though what really caused it. I did try to stay aroused a lot (two weeks or so?) but in the end directly before I discovered that the panties were stained some guy fingered me to orgasm on the bus. So yeah, not really sure.
But I also bought cum-stained panties I found in the thrift shop in town and that worked as well. My fans are perverts :)