Why, yes, i did actually!
Here comes the explanation...
I've had these things called "butterfly abs"...bought them years ago on some television selling show.
They're normally used obviously to stimulate your abdominal muscles.
Well, let's say they really suck on doing that...but, they do have a multiple variety of settings. You can choose intensity and the way they "shock" (with intervals, fast, slow...)
Sow, i decided "hey let's try these crap abdominal stimulaters for something else"...and you know what? They're great for nipple stimulation! First had to find the right settings, but after that, bingo!
So, yep like to use electro now and then.