My freshman year in high school a girl that sat across from me at our table grabbed my foot between her legs, took my shoe off and tickled me for a good 10 minutes while another girl came behind me and tickled my armpits. Very awkward to have a class staring at you. lol. But I got my revenge later, I actually bared her feet and tickled her. Turns out she was 10 times more ticklish than I was/am.
Then I believe during my junior year.. in my team sports class or something along those lines, doesn't really matter too much. Anyway, we had a free day to do whatever. So me and this girl went into the classroom and just chilled. She was sitting behind me and kept poking me with her feet. After a few times, I grabbed one of her feet and took her shoe off. Then I did it like a punishment, every time she poked me, I would take more off. She poked again, I took her sock off. Once again, I got her shoe off. Then she just said, "well now my foot feels weird." She took off her remaining sock and gave it to me. Then she was like, "now there's nothing left to take, I'm barefoot." So she poked me again with her bare feet. I grabbed one of her feet and held it with one arm and tickled all over it for a good 15 minutes. Now keep in mind I was in my gym class, so I was wearing the shorts they give you, now for whoever remembers those, you can see where I'm going here. lol. But it ended up with her telling me she loves her feet and then she dressed them back up. I had tickled them another 2 times or so since then but not at such a great extent.
My senior year.. my girlfriend thought me being ticklish was the cutest thing. So I constantly got tickled.