When I was in my early twenties, I dated this girl who turned out to have very sensitive hips. I found this out quite by accident. I tried sucking on the outside of her hip, as if i was trying to give her a hickey. Well, next thing I know, instant orgasm. Weirdest thing i've ever seen, but i thought "what the hell?" and just went with it.
Now, I tell that story, so I can tell this one. When my ex-wife and I first started dating, I thought ohh, let's do that same trick I'd done with the previous girlfriend. I think I even bragged to her, something like prepare to have your mind blown, or wait until you feel this, fully expecting to get the same result. Well, she kicked, screamed, clawed, fought for dear life, trying to get away from me. She had never felt anything that ticklish in her entire life. Now I've tickled her feet drenched in baby oil with a hairbrush, and she would still rather i do that than go anywhere near that spot. I was never allowed near there again!