The Shaggy Dog (1959)

 

From Wiki- The Shaggy Dog is a 1959 American fantasy comedy film produced by Walt Disney Productions and loosely based on the 1923 novel The Hound of Florence by Felix Salten. Directed by Charles Barton from a screenplay by Lillie Hayward and Bill Walsh, the film stars Fred MacMurray, Tommy Kirk, Jean Hagen, Kevin Corcoran, Tim Considine, Roberta Shore, and Annette Funicello. The film follows a teenage boy named Wilby Daniels who, by the power of an enchanted ring of the Borgias, is transformed into a shaggy Old English Sheepdog.

The film was released on March 19, 1959, and grossed over $9 million during its initial release, making it the second-highest-grossing film of 1959. Its success led to a franchise of further films, beginning with the 1976 sequel The Shaggy D.A..  Back to me:

I saw this in about fifth grade and thought it was hilarious.  I have probably seen it a few more times, but by now it has been three decades.  It is kinda funny, still. I saw The Shaggy DA, which wasn't quite as funny.  Haven't seen any of the other franchise stuff.