There are dozens of phobias in the English language, including Phobophobia, the fear of phobias. Phobias may seem silly but they can severely impact a person's life if not treated and dealt with properly. Learning about phobias, however, can be a fun linguistic exercise.
A few of my favorite ones:
Tonitrophobia: fear of thunder
Porphyrophobia: fear of the color purple
Genuphobia: fear of knees
The human brain is a mystery!