Happy Happy Christmas

"Happy Happy Christmas", or "it is a mystery", is the name given to a chiptune song made by Thomas Mogensen, also known as Drax. The song became well known after being used in the video "it is a mystery".

History
The song "Happy Happy Christmas" was composed by Thomas Mogensen through FastTracker and published on around December 1998.

Later, as part of the collective group Maniacs of Noise, he arranged a variation of this theme for the game , a German-exclusive GameBoy Color game published by THQ in 2000. It is the 6th track of the game: "Sub Tune #1 (Jolly)".

On April 27, 2011, the YouTube channel PIFTS.exe uploads "it is a mystery", a video using "Happy Happy Christmas" and displaying a pixel sprite of a ghost next to the text "it is a mystery". The video gained popularity, making the song well-known.

Rips
"Happy Happy Christmas" first appeared on the SiIvaGunner channel with the rip "Your Best Friend (OST Version) - Undertale" on September 16, 2016.

The melody has since been used in several high quality rips, including "Merry-Go-Round (Alpha Mix) - Super Mario 64", "Mysterious - Mario Paint" and "Track 6 - KRTL: Jay und die Spielzeugdiebe", a rip of the original chiptune where the song is changed to be "Happy Happy Christmas".

Since the video "it is a mystery" is associated with a ghost sprite, the song has been approved to be used as a source in both Halloween Horror Specials, despite the song being actually called "Happy Happy Christmas".