What is "pig-hoo-o-o-o-ey"

"Pig-Hoo-o-o-o-ey" is a short story by P. G. Wodehouse, which first appeared in the United States in the 9 July 1927 issue of Liberty, and in the United Kingdom in the August 1927 Strand. Part of the Blandings Castle canon, it features the absent-minded peer Lord Emsworth, and was included in the collection Blandings Castle and Elsewhere (1935), although the story takes place sometime between the events of Leave it to Psmith (1923) and Summer Lightning (1929).