Wikipedia
Ooh-Wakka-Doo-Wakka-Day
Ooh-Wakka-Doo-Wakka-Day is a 1972 song by Gilbert O'Sullivan. While it only made #8 on the UK Singles Chart, it was the first of three #1s on the Irish Singles Chart for him.
The song was never released on a studio album, but in 2012 made it on to a remastered version of Back to Front.
In 2013, a single-purpose version of the song which featured 300 people singing a reworded version of the song whilst going about their daily lives was used for an advert for the National Lottery.