Ever had an Idiotic Eureka Moment?

For those unfamiliar with the the concept, an Idiotic Eureka Moment is where you suddenly realize something that has always been common knowledge to everybody else.

For instance, last week it finally dawned on me that banoffee pie gets its name from a combination of the words banana and toffee. I'm 30 years old...

So, do you have any Idiotic Eureka Moments you'd care to share?
Ever had an Idiotic Eureka Moment?
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