Eliza Doolittle being the character from the book and movie, that is. The day was founded by Helen Chase who wanted to honor a woman (character) who demonstrated the importance of speaking the language properly. I'm not nearly as fussy about the language, but I love the concept of this story. Here's the trailer from the movie.
And here's an old Heineken commercial that spoofs Eliza Doolittle. A woman can't seem to curb her tendency to speak the language properly until she gets a taste of a Heineken.