The title is a play on "corn on the cob."
On Halloween night, Granny is shopping for candy at a local grocery store. The next customer is an armed robber, who is wearing a blouse and skirt identical to the real Granny. Policemen Daffy and Porky are given the suspect's description and attempt to apprehend the robber.
Most of the rest of the cartoon depicts Daffy and Porky confusing Granny with the actual suspect because of their identical clothing, and bungling their attempts to capture the crook. An annoyed Granny, who has no idea what is going on, mistakes the inept policemen for mischievous trick-or-treaters and mistakes real trick-or-treaters for juvenile delinquents, while the robber, who is hiding out in a vacant apartment in the same building in which Granny is living, also foils every attempt by Daffy and Porky.
Eventually, Granny figures out what is going on and catches her "double." After giving the suspect a spanking, she hands him over to Officer Flaherty. Flaherty commends Granny for catching the robber, after which Granny tells him "there are two other juvenile delinquents" who should be sent home to their parents, referring to Daffy and Porky, but when she asks for their addresses, Daffy gives her their precinct address and begs her to back off.
- When Porky makes his comment on Daffy's bad carpentry while taking out the wooden bridge's nails, his mouth isn't moving.
- On both ABC and The WB, the part where Daffy is shot in the face by the robber dressed as Granny was cut.
- This cartoon marked the final theatrical pairing of Daffy Duck and Porky Pig during the Golden Age of American Animation.
- This is the final official appearance of Porky in the Golden Age of American Animation.
- This is one of the few DePatie-Freleng era shorts to not feature Speedy Gonzales with Daffy Duck, the other two being "Suppressed Duck" and "Tease for Two".
- This is the final appearance of Granny in the Golden Age of American Animation.
- This is the only time that Irv Spector, who was mostly known as a story artist, ever directed a theatrical short.
TV Title Cards
- "Corn of the Cop" at SuperCartoons.net