To Joybell, regarding the difference between the Cajun ladies' frottoir and the armor bras featured in Wagnerian opera:

I don't believe those opera costumes feature the requisite corrugation.

Actually, I believe the playing surface (ridged area) is confined to the below-the-boobs zone, at least on the *standard* model. If a player really wanted to tickle herself, of course, there's nothing to prevent her from tapping any area of the breastplate with her thimbled fingertips.