According to folklore, you get pinched on St. Patrick’s day for not wearing green because green makes you invisible to leprechauns, and leprechauns like to pinch people (because they can!).
Apart from the superstitious aspect, you might also be wondering, “Why do we wear green on St. Patrick’s Day, anyways?” Well, wearing green actually symbolizes Irish Republicanism, a nonsectarian movement from the late 18th century that campaigned for Ireland to become an independent republic.
The reason green has so deeply become entwined with St. Patrick’s Day came a little bit later, says Time. In the 19th century, Irish immigrants started landing in America and celebrating St. Patrick’s Day and their heritage by wearing this symbolic color.