The Whacking Day song is certainly in the files so it may well feature in the game should there actually be a Whacking Day event (although, I suspect, as words only).

For those of you who haven’t seen the episode, the words are below (sung to the tune of Oh Christmas Tree). But before posting comments on animal rights, please remember that this was done with the usual Simpsons irony (which was much more common in the early years) and that the episode was written to highlight the mistreatment of snakes. It remains to be seen if any Whacking Day event appearing in the game follows the episode’s lead:

Oh Whacking Day! Oh Whacking Day!
Our hallowed snakes skull-cracking day.
We’ll break their backs! Gouge out their eye!
Their evil hearts we’ll pulverize!
Oh Whacking day! Oh Whacking Day!
May God bestow his grace on thee.

So you can hear how the song sounded in the episode when sung by the children of Springfield Elementary, here’s a link to an audio of the song on YouTube uploaded by swingballbros:

And here, to be fair to the snakes, is a link to the song that the late, great Barry White sang (with a little variation) to help end the Whacking Day tradition in Springfield and save the snakes forever, uploaded to YouTube by Christopher Cabrera (with Spanish subtitles):