(as) easy as rolling off a log

Extremely easy, simple, or intuitive; requiring very little skill or effort. After so many years as an accountant, doing taxes is easy as rolling off a log. A: "I'm a little nervous about learning how to drive." B: "Don't worry. After some lessons and a bit of practice, it's as easy as rolling off a log!"

Not difficult; requiring little or no effort. One writer claims that this term, which is American, dates from colonial times, but the earliest written records date from the 1830s. Mark Twain used it in A Connecticut Yankee in King Arthur’s Court (1889): “I could do it as easy as rolling off a log.” The analogy, no doubt, is to remain standing on a log floating downstream, which is no easy feat. Indeed, it is sometimes put as easy as falling off a log. See also duck soup; easy as pie.