Chippy is the song composed by Kevin Schilder for Hexen.
According to the Doom Wiki, Chippy was the name of a pet hamster Kevin Schilder had as a child.
Hexen: Beyond Heretic (DOS)
Chippy plays in Orchard of Lamentations of Hub 3 (pictured). Only the MIDI version of the song comprises the soundtrack. However, if there is the music CD inserted the game will instead play the track number 22 (corresponding to Simon).
The internal name ("lump") of the MIDI track is chippyr.