I have a friend who is obsessed with bellybuttons. She will be surprised to learn that her poke-and-sniff hobby is a little dirtier than she thought.
Recently, research tested 60 bellybuttons and identified 2,368 types of bacteria living there. 1,458 of those species may be new to science and many of them are very random. For example, one guy had a bacterium that is only found in the soil in Japan. He has never visited Japan.
Bonus fact: bellybutton lint comes from your underwear and not your shirt.