I hate to admit it, because I like to be very professional at work(I work as a massage therapist). If I hit a spot that needs work, but it tickles the hell out of my client, if I do it long enough, I find myself getting a little turned on. I obviously never ever act on it, as I do have a high ethic moral, but it's just my body's reaction to laughter and squirming. It's worse when they affirm their ticklishness by saying things like "Omg, that tickles so much" or "omg, that's such a ticklish spot for me" or "I'm so ticklish, it's ridiculous" and then continue laughing.
I had a client who was not only cute, they have very nice feet, and a service I gave them was a foot scrub, and it tickled the hell out of them and they admitted it felt good despite it tickling. I had to use the bathroom afterwards to just clean myself off

Honestly super embarrassing for me