Like Shelling Peas
(simile, idiomatic) repetitive, but very easy.
Example: 1996, Stephen Smith, Parentcraft, p. 14:
Do you know that some people, no matter how much money they have or how far medical techniques improve, will never be able to have children while for others it's like shelling peas?
2007, Peter Arden, Supergeek, p. 74:
At school he could deliver straight A's like shelling peas.
2010, Leo McKinstry, Geoff Boycott: A Cricketing Hero, p. 43:
They just rolled my wicket over and said it was like shelling peas.