How did you survive...?
I used to think babies just popped out of females.
I'm sure a few people've had this one, but I thought America was all there was in the world. Sticking with this geographically ignorant theme, I used to think that the house we went to in the summer with my grandparents was "Maine." Like, just the house.
I actually didn't know how to properly masturbate (i.e. with the result of an orgasm) until I was 19.
Please don't ask me to explain that.
When I saw Ace Ventura for the first time, I didn't understand the ending when Lois Einhorn was actually a dude because you could see her junk through her underwear and my dad kept telling me that she just had a bad case of hemorrhoids.
I was often confused to the alignments of colors when I was little; red was usually/always bad, and blue was good - but white was also good; so eventually I had white and blue fight to the death to see which color was essentially "more good".
Good times.