Her: You know, tigers and lions are basically the same animal.
Me: ...What? No, they're not.
Her: Yeah, they are! The tiger is the boy and the lion is the girl!
Me: You are SO stupid!
But she persisted for around ten minutes until I went in the kitchen and asked my mother who was right. We still make a mockery of my sister over this.
Turns out, she had been told that by one of her older friends (over forty years old, and on a ton of pain pills). I find it unbelievably sad.