piece of cake
Attested since 1936, originally in American English. The notion of facility probably derives from many cakes having agreeable tastes, and hence being ‘easy’ to consume.
- Used other than as an idiom: see piece, cake.
- (idiomatic) A job, task or other activity that is pleasant – or, by extension, easy or simple.
- Sure, no problem. It'll be a piece of cake.
- (an activity that is easy): breeze, cakewalk, child's play, cinch, doddle, duck soup, walk in the park, walkover
- See also Wikisaurus:easy thing
simple or easy job