Big time, a single finger is enough to cause a lot of tickle damage on the armpitsHm, that's a good question.
Armpits to me are a great ticklish centerpiece of the entire upper body. You're never far away from all the other good spots like nipples, ribs, abs, sides and hips, but it's not only that.
Armpits are smooth, soft, and very well protected, which makes my desire to tickle that spot even greater.
In order to get to them, the "victim" has to be restrained somehow, which make the whole thing even hotter.
Add to this the fact that, for many women, even slightly scratching their armpits sends them into a laugh frenzy...and damn.
I just can't resist tickling them with impunity at every opportunity.
The same with my ex wife. My first choice is feet, and hers were pretty damn ticklish! But head towards her pits, and she would start freaking out! Of course she'd be tied down with her arms pulled up tight and her pits totally vulnerable. I'd wiggle all my fingers about an inch away from them and start telling her how much it was going to tickle. She'd start laughing like I was already tickling them before I even touched her! Then I'd slowly start moving closer and closer. By this point, you'd think I had been actually tickling them when I hadn't even touched them yet! But you'd know when I did touch down! She'd let out a screech and go immediately into full blown hysterical laughter!In my case, it's because it's my girlfriends most ticklish spot. And that's saying something because the rest of her body is extremely ticklish already.