The musical MY FAIR LADY (written by
Alan Jay Lerner with music by Frederick
Loewe) is based on George Bernard Shaw's 
play PYGMALION. Though many songs from this
musical have entered the standard repetoire,
the most well-known is probably "The Rain in
Spain Falls Mainly in the Plain", which is
sung jointly by Eliza Doolittle, Professor 
Higgins, and Colonel Pickering towards the 
end of the third act.