Back when I was 3, my dad used to do his reserve duty in Washington, DC. My mom, sisters, and I would go down and meet him halfway through the two weeks. I would sit by my mom, and my sisters would sit behind us (they were older, and honestly better behaved!).
Back in the day, you used to get planes with a 3 and 3 configuration from Maine to DC - I'd sit at the window, my mom would sit in the middle, and a random person would sit on the isle.
One time, I wanted to try the middle seat. My mom implored me not to, but I wanted to, so she let me.
She woke up to hear me saying "tickle, tickle, tickle!" She looked over to see me tickling a very unamused Ralph Nader.