Fact
Sucking on a shared hookah mouthpiece can help spread herpes. Gives new meaning to the term "pass it around" huh?
Source 1:
"Hookahs." CDC. 14 Sept. 2015. Web.
http://www.cdc.gov/tobacco/data_statistics/fact_sheets/tobacco_industry/hookahs/
Source 2:
"Hookah Smoking: A Growing Threat to Public Health." American Lung Association. Report.
http://www.lung.org/assets/documents/tobacco/hookah-policy-brief-updated.pdf