A piece of cake

What does “A piece of cake” mean?

It is used to describe a job, or task, or sporting challenge, or other, that can be accomplished very easily. Often it is used to impress the listeners with a persons skills or prowess in that area; showing off!

I cycled that route before in under an hour. It’s a piece of cake.

Person, showing off their skills in cycling by stating that a cycle route is “A piece of cake”