She didn't know but she was terrified of the ride.
Why didn't she want to go on the ride?
She didn't want to go on that ride because she's afraid of clowns.
Clowns are terrifying. You should have asked her if she wanted to go on the ride before going on it. She was probably really upset when she found out that there were clowns involved.
Clowns are scary. I don't blame her!
I think that it might be better to find another ride. If you are both scared, I can see the obvious solution.