Two sisters
There were once two sisters, one called Petal and one called Fridge. One day, Petal asks her parents, "Why did you call me Petal?" and they replied "Because just after you were born, a petal fell on you."
"Bllaaarrarararraraaarg", says Fridge from the corner.
Edit: neat, near the top of /r/jokes frontpage! That's, cool, thanks!
And yeah, there's a few versions of this, but I found I had posted this as my status on Facebook about 6 years ago (along with a statement that I had…