想象一下，一块在街上随意行动的蛋糕非常容易被吃掉，所以a cake walk引申为"容易的事、轻而易举的事"。

Solving that math problem turned out to be a cake walk for the brilliant student.
对于这位聪明的学生来说，解决这个数学问题简直易如反掌。

take the cake
最佳或令人印象最深刻的东西

bake a cake before one can judge its taste
亲身经历之前无法去妄下评判

cake and eat it too
既要又要

not my piece of cake
不是我的菜、不是我擅长的

a cake in the face
当众出丑