Who started the tradition of pinching on St Patrick's day?

It's apparently an entirely American tradition that probably started in the early 1700s with Irish immigrants. Those celebrating St. Patrick's day claimed that wearing green made one invisible to leprechauns, who would pinch anyone they could see (anyone not wearing green). People began pinching those who didn't wear green as a reminder that leprechauns would sneak up and pinch green-abstainers.