How do you respond when someone accidentally does something traumatic to you?

I've had a similiar experience when I was very little. My uncle's friend, and family friend, kept tickeling me...I started out laughing, but then I couldn't handle it anymore and couldn't even cry because I was that worked up. Finally when he stopped he could see that I wasn't joking or laughing and I was bawling. I was around 4-5, but I let it go. He didn't know that I wasn't playing around and that I was actually upset about it.