Future Events!
I looked it up, and Talk Like a Pirate Day is far more famous than all the other ones combined. However:
March 13 is Talk Like a Physicist Day
April 23 is talk like Shakespeare Day
May 22 is Talk Like Yoda Day
July 17 is Talk Like a Brummie Day
For the record:
A group of physicists is called a "knot."
A Brummie is a person with a Birmingham, England accent. Psychiatrists have labeled it the least-trusted English accent, and TV villains often speak with a Brummie accent. There are about 1 million Brummies in the world.
There is no Talk Like a Parrot Day. It is a mispronunciation of Talk Like a Pirate Day.
There is no Talk Like a Ninja Day, because...
ninjas don't talk.