When I was a kid, my brother used to make up crazy things and I believed everything he said. Then, he'd embarrass me by pointing out my naivity in front of all his friends.
For example, we were watching baseball once, and I asked him what a double play was. He told me, "It's when you run around the bases twice." Now, I was only in kindergarten or first grade, so this seemed like a legitimate explanation. Some time later, we were playing kickball in the parking lot across the street. I, of course, started running for first base after I'd already reached home.
"What are you doing?" his friends shouted.
"I'm making a double play!" I proudly replied.
There was a trash incineration place across the street from the K Mart we frequented as kids. My brother told me the tall towers of smoke were in fact "cloud makers." To this day, we use cloud makers as a reference point in giving directions.
I was telling these stories in the office today, and my coworker told her own story. Her brother had cut Barbie's hair, and she said, "I'm telling! I'm telling!" Her brother calmly told her, "Don't worry about it. It will grow back." She waited and waited for days and days, but Barbie's hair never grew back.
Who duped you as a child? How?