When I was around 7, someone gave our family a box of these caramel-on-a-stick candies called 'brown cows' and my step-brother at the time used to say 'have a cow/ don't have a cow' referring to the candy. I'm 25 now so the Simpsons wasn't on at the time but the first time i heard the phrase 'don't have a cow' i was convinced that someone on the street heard our family saying it and immediately dialed hollywood up and relayed this wicked-cool phrase that they'd heard a child say on the street.
i thought we invented 'don't have a cow'
A childhood belief about speaking

others believed things like this
- I was about 6 and thought my family invented the fart because I never heard anyone outside my family do it.— Bob
- I believed for a long time that brown cows gave chocolate milk!— Evil Mom
- I heard a mother in the street tell her young son not to pick his nose...because his head would cave in. — Ruby
- As a kid every time I heard a person say "it's about time" I always replied "so what about it?"— Eli the Kid
- The first time i heard of someone getting fired from a job, i thought that they were actually set on fire.Anon
- When I was young, I heard the word 'minion' for the first time and thought it was a miniature onion.— Karin