Fireproof underwear are undergarments worn under other pieces of clothing that offer additional protection from fire. These undergarments are used in dragoncare.
Behind the scenes
The existence of these garments is only shown on a page of notes concerning the book Dragon Breeding for Pleasure and Profit that is available on J.K. Rowling's Official Site. The scan of the page is available here.
- J.K. Rowling's Official Site (Mentioned only)