there was always the "you keep eating ____ and you're going to turn into one" I never wanted to be a Reese's Peanut Butter Cup so bad in my life, all I got was sick.
"It takes one to know one" and in all honesty I never realized the fucked up insinuation until just now.
Santa, which I happily ruined for my sister when she was around 6-8 by pointing out that Santa had the same handwriting as dad and the box her shiny new bike came in was sitting by the garbage cans on the side of the house. I regret busting that one because that was the last year we got the kick ass Santa gifts unwrapped and ready to play with first thing x-mas morning.
The Easter Bunny, but even as a kid I knew that didn't add up at all, I just went along with it to ensure I still got my basket full of goodies from him every year.
OH OH OH and this one was great from my dad "If someone hits you, you hit them back" I tried that, I got suspended and grounded and my ass beat by him for doing what he told me I should do.
And my Grandma still believes the lie that you cannot let cats near a sleeping baby because cats will sit on the sleeping baby's chest and steal there breath (something about the sweet smell of breastmilk on their breath attracts the cat).
That they would never make comparisons between my sister or my dad when he was a kid and myself (in relation the school/grades) because it was unfair to hold expectations based on someone who is nothing like me. A month later my dad rubbed all his old report cards in my face and yelled at me because at my age he was getting A's and B's while I was puling straight D's.
I now understand having kids of my own that they are more apt to believe the lies than the truth anyway, especially about where babies come from. When we told our oldest about how babies are really made he laughed and called us both liars. We also hold up the Santa bit, I'm not really sure why because I remember how betrayed I felt as a small child learning the truth of it.