It comes from a 1970's british TV commercial for Lemon Squeezy detergent. They were with a little girl who points out dirty greasy dishes to an adult (mom or relative) and then this adult produces Lemon Squeezy and they clean the dishes quickly. At the end of the commercial the girl says "Easy Peasy Lemon Squeezy".

Today it is a silly way to state something was or will be very easy.
I will be in an out, easy peasy.

Can you open this jar of pickles? Sure thing easy peasy.
by Creepy Gnome August 2, 2009
1. The first half of a rhyming phrase with several alternate second halves, all of which connote an activity or a result that is, respectively, simple to perform or achieve: Very Easy

2. An operating system based on Ubuntu for netbooks: www.geteasypeasy.
1.
18 pints? Easy Peasy!!
Tie your shoes? Why that's easy peasy lemon squeezy!
Beat your meat? Why that's easy peasy Japanesey!
As a red-stater, condemn books and films without having read or seen them? Why that's easy peasy puddin'n'pie!

2.
I just installed Easy Peasy the other day
by ramvi February 23, 2009
(uk) very easy (short for easy-peasy-lemon-squeezy)
18 pints? easy-peasy!!
by dilbert scrunchie June 20, 2003
the first half of a rhyming phrase with several alternate second halves, all of which connote an activity or a result that is, respectively, simple to perform or achieve.
Tie your shoes? Why that's easy peasy lemon squeezy!
Beat your meat? Why that's easy peasy Japanesey!
As a red-stater, condemn books and films without having read or seen them? Why that's easy peasy puddin'n'pie!
by the sobsister December 9, 2004
easy - peasy is is what it's like to be butt-fucked by a guy with a small dick after you've had your cherry-hole busted and stretched a little.
Since Matt has fucked me with his 8" dick, taking a 5" dick is easy - peasy!
by USAF Cadet September 24, 2021
slang phrase (from an old British detergent commercial) used to express that something was quickly and easily done.
the claim processes was easy peasy lemon squeezy
by nick_f November 4, 2009
When an event or an action is uncommonly unchallenging to execute or to obtain.
When I found the tools, fixing the bike was easy peasy lemon squeezy
by Dorkus van Hooff June 20, 2015