Anything that can be done with straightforward ease is said to be a "cakewalk." Any action that is "not a cakewalk" is, of course, difficult and complicated.
No surprise, right? But stay with me a little longer.
The cakewalk was a pre-Civil War dance originally performed by slaves on plantation grounds. The uniquely American dance was first known as the "prize walk"; the prize was an elaborately decorated cake. Hence, "prize walk" is the original source for the phrases "takes the cake" and "cakewalk."