She told me she was scared of clowns
And how did you respond to her being scared of clowns?
I just laughed at her, she can be so dumb sometimes. What's there to be scared of?
There are a lot of things people are scared of. It's insensitive to judge her because she has a fear of clowns. What you think is not scary doesn't mean others think the same. You should respect people for who they are and what they like and don't like.
This "fear" of hers is bullshit, and she needs to get over it.
Her fears are her fears. You don't have the right to belittle that. Instead of laughing and brushing her off, help her overcome this fear.