I did this lesson last week with my high schoolers. I began the lesson by asking them what they have a fear of (spiders, insect, mouse). I then gave them a brief definition of a phobia and told them three phobias I have and asked them to try and guess what they are. I then gave the class six examples of phobias and showed them some youtube clips of fear factor. I then asked them to work in groups and create a phobia and explain it to the class. The lesson went pretty well and got some interesting phobias. I posted the lesson Waygook and the lesson can be found by following this link.
PS. You must join waygook.org if you want to download the lesson to use. Waygook is a great resource site and has a very active community. It’s well worth checking out.