Man...in my case it was multiple behaviors and events combined with the classics most people here eventually go through:
- I remember being 11-12 when making up games during family gatherings as an excuse/attempt to tickle my female cousins. One game we would play would be me chasing them and then tickling whoever I caught first. I must have had a latent armpit fetish back then, since I would always go for the same cousin, who had the most ticklish armpits and often caught wearing tank tops. After catching her, I would just wrestle her down, pin her arms and go to town on her armpits. Later I would learn she actually enjoyed this, but that's a story for another time.
- At 13, I woke up covered in my own jizz after having had a dream about tying up and tickling my crush....I never stood a chance.
- I always thought I only liked tickling others. But then one random afternoon I am chilling with my older sister and one of her friends. They are like 15-16 at this point, discussing what to do since they're bored out of their minds. We are all laying on my parents bed watching TV. Her friend out of the blue says...."We should....tickle your brother..." as she says this I feel a fingernail stroke the length of my sole, I clench my toes, hold the laugher in and let out a muffled giggle. My sister says "Ew...no...", she never really tickled me growing up, and found me annoying as fuck, she was my sister after all. Then my mom calls my sister and asks her to go help her carry the groceries so she jumps off the bed and leaves. The moment she leaves the room this girl I barely knew locks my ankles with one arm and proceeds to tickle the hell out of my soles. I'm laughing, screaming and contorting. She stops, I think it's done. Then she jumps on my back and jabs her fingers into my sides...I jump and squeal and cannot stop laughing like a maniac. Then we hear my sister and mom coming and she just leans in and says..."You're cute" and gets off me. It was intense and the whole thing probably lasted less than a minute, but I remember it vividly to this day. That's when I realized I also liked being on the receiving end.
- Turning 14, I discovered internet tickling content and there's that. I was so turned on by that shit I could cum by just watching the video, didn't even have to move.