What do you mean "at a loss of words" (I have a specific definition that may make your answer incorrect)
In the original Mary Poppins film, Mary wins a horse race and is surrounded by reporters. The reporters suggest she is at a loss of words, to which Mary responds saying there is at least one word appropriate for the situation and begins the song.
As for the Rodney Pattison one, the Dinghy he used in the 1968, 1972, and 1976 games was called the "Supercalifragilisticexpialidocious"