Note: This site, as you probably know, has quite a few idioms on it. If you're not entirely sure what an idiom is, well, consider looking at a few examples of idioms to get a better idea on what they are. If you already know, then let me give you a little reminder that we have an alphabetical list containing the meanings for numerous popular sayings, and it's just a click away, so feel free to search for more. If you are unable to find a particular phrase that you're searching for, then perhaps check back another time as more will be added later on.
KnowYourPhrase.com - Sayings and Phrases - Meanings and Origins
An activity that requires little effort to finish; a job that's simple; easy.
When a task is easier to complete than previously expected, people might use this phrase to express those thoughts.
The origins of the phrase 'a piece of cake' are not certain.
There's an expression that's similar to this one that goes 'as easy as pie.' The meanings for both of these sayings are identical—they convey the idea of simplicity. Why is that? Well, the origins for this saying are not known, as previously mentioned. However, if one were to guess, then it's doubtful that the figurative meaning derives from the baking aspect of making a cake, since that requires a decent amount of work. Do you know what is easy to do, though? The eating part, because cake tastes great! So perhaps the figurative meaning of this phrase comes from the ease of eating cake?
Anyways, this saying goes back to at least the 1930s. The term was used with its figurative meaning by an American poet named Ogden Nash, who wrote a book called Primrose Path in 1936. There's a part from it that reads:
"Her picture's in the papers now, And life's a piece of cake."
* This upcoming bicycle race will be a piece of cake for me because I've been going through exhaustive training sessions these past few months to prepare myself for it!
* The roof was leaking, so Jake climbed to the top of his house to fix the problem thinking it would be a piece of cake, and it was!