Easy peasy is a common, if silly, way to express that something will be very easy.
It first appeared as children's slang in the late 60s (perhaps earlier, but it's hard to be certain, as children don't publish much); it seems to be a case of simple rhyming reduplication. Until the 1980s it appears to be mostly limited to the United Kingdom, where it also grew into the extended version "easy peasy, lemon squeezy". Some people insist that they have heard this phrase as part of the Lemon Sqezy advertising campaign, but there is no hard evidence of this; it is just as likely that the popular brand of dishwashing soap provided a happy opportunity for kids to expand the rhyme, without any intervention from the marketers.
Easy peasy and its lemon squeezy are now common enough throughout the English speaking world (but let me know if you live in a country that hasn't picked it up yet!) and has stayed strictly true to its original usage.
Not what you expected? You might be looking for EasyPeasy, a version of Ubuntu optimized for netbooks.