system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is the skin on bald men's heads shiny but skin everywhere else on the body is dull?
gpt
Your head secretes an oil called sebum and it still does so even after you lose your hair. Not washing your hair for a few days will make it oily, the same oil makes your bald head shiny without the hair.