British neurologist John Hughlings Jackson once said that the first man who insulted another person instead of “knocking out [their] brains without a word” actually laid the groundwork for civilization. An insult can often feel like a sudden, painful slap to the face. But if you also show the middle finger, it can push some people into a full-blown tantrum. A nasty gesture can be costly Obscene hand gestures and vulgar puns permeate all areas of life — from supermarket checkouts and road rage situations to everyday conversations. Social media comment sections are especially rife with crude ges…