(as) easy as A, B, C

See: as easy as pie

• an ivory tower
• a nod's as good as a wink.
• an old chestnut
• an old flame
• an old hand
• an old head on young shoulders
• an old maid
• an old wives' tale
• an olive branch
• a no-lose situation
• a non sequitur
• an open book
• an open marriage
• an open sesame
• a nose for
• a nose for something
• a nosey parker
• a no-show
• a nosy parker
• a notch below
• a notch below someone
• a notch below something
• another bite at the cherry
• another nail in the coffin
• another string to bow