On the island of Portland, in the county of Dorset, in the south of England, there is a local custom of not referring to those rodents by their common name. I'm not sure what the people there say on the first day of every month, but long-eared, furry pie-filling is probably not used.
Actually, this may be the reason:
Real-life Ponty Python attack bunnies routed Napoleon Bonapart and his men.
Link: How the great Napoleon and his men once surrendered to an army of attack rabbits. [sites.psu.edu]