Lepidopterophobia is the fear of butterflies. While these delicate creatures may seem harmless to most, for some, their fluttering wings can induce fear.
Arachibutyrophobia is the fear of peanut butter sticking to the roof of the mouth. It's a humorous fear, considering how common peanut butter is in many households.
Hippopotomonstrosesquippedaliophobia is the fear of long words itself, which can be quite ironic and humorous due to the length of the word describing the fear.
Xenophobia is the fear of the unknown or foreign, which can be amusing in a way since it's a fear of things that are unfamiliar rather than specific objects or situations.