If you haven't already figured this out, I live in the oral cavity of humans. Yep, it's pretty sweet living inside a mouth. And not just like 1 out of 10 human oral cavities. I'm in them ALL. I am currently hanging out in your teeth, tongue, saliva, and cheeks. Making up about 30-60% of the total bacteria that inhabits everything in everyones mouth. 

4) Allmann, A. (n.d.). Habitat. Retrieved November 28, 2016, from http://bioweb.uwlax.edu/bio203/s2007/allmann_ambe/habitat_and_geography.htm

Photo citation:

http://c2.thejournal.ie/media/2014/09/mouth-6-390x285.jpg