1. n. a baseball that drops straight down into the glove of a waiting player (for an out). (Since the 1940s.) It’s a can of corn! Right into Sammy’s mitt.
2. n. something that is really easy [to do], as in easy as catching a can of corn. (From the image of an old-time grocery store clerk who would grasp a can from the top shelf with the special long tool, and then drop it straight down into his hand.) Nothing to it. A can of corn.