Or…. Sunday sex represents the beginning of life, while Saturday represents Death and rest, like the 7th day versions have it. Kicked out of Eden because sex accelerates evolution, and the exchange for being too good at sex (search “insects”) is early death to make room. Life that clones itself is immortal, but slow to change. Weeeee!!!!!! Sunday isn’t just Fuck day, it’s FUCK IT! WHOOPEE!!! day. ;)