Homeopathy is a "medical" treatment that does not help people get well. The idea of it is to treat people with incredibly dilute solutions of purported medicines. As ridiculous as it sounds, it is still quite popular.
Examples of modern Homeopathy:
It is easy to say buyer-beware, but fevers can have serious consequences. Using these treatments instead of real medicine can have serious consequences.
Homeopathy is an excellent phenomena to explore pseudoscience as well as the mathematics of dilution. Explore it with your students using the Homeopathy Lesson: Delusion through Dilution.