And extremely common one in my cultural (USA) context is that "being cold" can give you a "cold". According to common wisdom, being out in cold weather with wet hair and no hat will cause you to be infected with a rhinovirus.

The expression encapsulating this is "You'll catch your death!"

When travelling in Eastern Europe, I found a similar attitude towards drafts from a couple locals. The safest was to keep all windows and doors to the outside closed (in a room or car). Opening one portal was frowned on. Two or more (creating airflow) was taboo and would cause sickness.