Katherine's gonna LAUGH, dammit!

Katherine is excruciatingly ticklish on her feet, but for some reason, she never was a laugher when you tickle her. She gasps almost orgasmically, she thrashes, her foot almost vibrates trying to get away from the tickling, but you really have to get EVIL if you want to get laughter out of her. So even though I start soft with just my (long) fingernails) and a short interlude with a feather between her toes, eventually I just want to hear her laugh, and I'm going straight to the massager, at which point she's thrashing and there's the laughter! I am holding her foot still by grasping all the toe ties so her foot can't even move, and then I'm slowly and agonizingly dragging that thing all over the balls of her feet until she goes nuts.