"Blue (Da Ba Dee)" (also released as "I'm Blue" in some countries) is a eurodance song released in 1999 by Italian group Eiffel 65, as a single from their debut album Europop (1999). The meme that comes from it consists of several options:

1) Using blue tinted images/videos set to the song,
2) Pertaining to Sonic the Hedgehog (since he's blue),
3) Misheard lyrics for the Da Ba Dee sections, or
4) Pitch-shifting existing material to the song.

On Jul 21, 2008, YouTube user malawolf85 posted a simple video using the song and a single image. The video has since gotten over 5,000,000 views (5,468,244 as of July 25, 2011), and is considered by many to be the video that kick-started this meme.

However, in the previous year, user Pikachu1391 uploaded a video called "Sonic and Friends Sing 'Blue (Da Ba Dee)' ".

This video was also quite popular, snatching about 1,552,000 views so far. Other people say this was the video that started it.

Other people say it was EOPkers' 2,000 view video "Im Blue – Runescape Style – With Lyrics"

Most people dismiss this as the origin, because of the relative unpopularity. The origins are actually rather untraceable, as there are over 1,400 deviations of it on YouTube alone. It even recieved it's own techno remix!

Other notable variants include:

thanos134ever: Spongebob sings I'm blue (Most viewed in fan-made category)

jhnhlh – Gummy bear i'm blue (See also: Gummy Bear Song)

craZelz – I'm Blue (Da Ba Dee) Shark

TheNubCupCake – Gottam 65 – Im Blu (Gottam Gottam) (see also – GOTTAM)

davy050995 – Alvin and the Chipmunks- I'm Blue (See also – Chipmunk Versions)

WhatisLOVEallvideos – What is Sonic (Eiffiel 65 Version) (See also – What Is Love)

CDplayer0 – Im Blue BACKWARDS

GIRakaCHEEZER – Kirby is Blue