So I tried to break away from the usual HUMP day scene and substituted it with a similar sort of hump, a butte. Butte day. Why not?
I feel like it represents more: hump day represents the day when we have made it to the top of the theoretical hill (hump), or butte, and are now on our easy way down. Just look how steep that butte is! Many people face this sort of hardship week to week, which makes the butte a much better candidate for having its own day.
Happy butte day!