"It's a Hap-Hap-Happy Day" is a popular song with words by Sammy Timberg & Winston Sharples and music by Al J. Neiburg. It was featured in the animated feature film Gulliver's Travels in 1939. It was a hit in the UK in 1940 during the Battle of Britain, having been played heavily on the BBC radio.
Notable recordings
References
It's a Hap-Hap-Happy Day Wikipedia(Text) CC BY-SA