The Sin of Harold Diddlebock is a 1947 American comedy film written and directed by Preston Sturges, starring the silent film comic icon Harold Lloyd (in his final film appearance), and featuring a supporting cast including female protagonist Frances Ramsden, Jimmy Conlin, Raymond Walburn, Rudy Vallee, Arline Judge, Edgar Kennedy, Franklin Pangborn, J. Farrell MacDonald, Robert Dudley, Robert Greig, Lionel Stander and Jackie the Lion.

It was quickly pulled from distribution by producer Howard Hughes who took almost four years to re-shoot some scenes and re-edit the film,[3] finally re-releasing it in 1950 as Mad Wednesday – but the reception by the general public was no better the second time around.

When Harold tells the bartender, Jake, that he has never had a drink in his life, the barkeep creates a potent cocktail he calls "The Diddlebock".

In the midst of his transformation, Harold overhears Wormy talking with his bookie Max, and impulsively bets $1,000 of his money on a 15-to-one long shot horse named Emmaline.

To everyone's surprise, Emmaline wins, and the now-rich Harold celebrates all around town on a day-and-a-half binge of spending, gambling, and carousing.

Unable to remember much about his drunken binge, Harold goes to return the plaid suit and is surprised to learn that he now owns a horse-drawn cab, complete with an English driver named Thomas.

Harold and Wormy visit the circus-loving Wall Street banker Lynn Sargent, but he turns them down because he is trying to unload his own bankrupt circus.

To get past the bank guards, Harold dresses up in his plaid suit and brings along Jackie, a tame circus lion, who incites panic.

Carrying a filled Thermos, Wormy gives shot drinks of the potent "Diddlebock" cocktail to each of the bankers they visit so their inhibitions will fade and convince them to put in bids for ownership of the circus.

They find that the publicity has attracted a mob of bankers at the jail who want to buy the circus – but Ringling Brothers outbids them.

[1] Although the project began as a labor of love between Sturges and Lloyd, the two had a disagreement over creative differences, which affected the quality of the finished film.

California Pictures was a new company and lacked adequate facilities to make the film, so Sturges attempted to buy Sherman Studios.

According to All Movie Guide's Hal Erikson, the shorter version plays better for audiences, while the original is richer in its comic invention and characterizations.