I know this is a realitively "young" crowd, but is there anyone else out there who remembers this this old 1985 movie titled "The Peanut Butter Solution". In it, this kid loses all his hair and tries this potion on his head to get it to grow back. It turns out the potion had too much peanut butter in it, so the kid's hair grows too fast. Some villain captures him and uses his hair to make paintbrushes and that's how his friends track him down and free him.
Apparently, it was also a book... and the movie had some other kid put the "solution" on his "other hair" and that grew rather fast-like as well.... gross >_<