The premise of this song is just wacko: this kid has decided that his usual Christmas haul isn’t enough, and so this year, he’s going to rob Santa at gunpoint.
There are almost no details about this record available on the web, so I cannot speak to why people thought this up, recorded it and then sent it out into the world – especially in 1963, when a jolly song about shooting Kris Kringle might not have been every American’s cup of Christmas tea. Though, given the available info, maybe it’s better that we don’t know?