The "Bump" is a tumor which often infects the hair of celebrities.
Several people of note have been infected. Here are some people not-of-note who have also been infected:
Researchers are still investigating the possible link between blonde hair and "Bump" infections. They are also trying to separate the real cases of "Bump" infection from fraudulent ones. The imposters are wearing these hair-covered torture devices:
The sick masochists.
Upon its first appearances in the early 21st century, scientists have been unable to find a probable cause for the "Bump." There is still no clear understanding of its biological structure, as a dissection has yet to take place. Scientists have, however, discerned that the "Bump" has a sentience of its own, and may well control the mind of its host.
No one has seen what the "Bump" looks like underneath the hair. Early speculation suggested that it was merely a third breast protruding from the top of the head. More radical thinkers are now accusing "Bump" victims of being members of an alien race, bent on Earth's destruction.
Observed and proven side effects of the "Bump" include heavy-headedness, balancing difficulties, illusions of having a larger-than-normal brain, weight gain, and a sudden-but-very-real-fear of low doorways.
Mind control is still being investigated as a possible side effect. Excessive and overwhelming hair growth is another possible outcome of the "Bump," and in rare cases even fatality, or this:
There is only one.