The middle of a work week (Wednesday); used in the context of climbing a proverbial hill to get through a tough week.

Wednesday, or the hump of the week
The absolute BEST day of the week, the day of maximum hope that maybe, you might make it out of this week alive. A particularly good hump day can last you the rest of the week, and by Doomday morning (Monday) you survive by anticipating hump day. Nothing goes wrong on hump day

Most other days can be defined by hump day. Tuesday is the day before hump day. Thursday is one day after hump day. Except Friday is WOOOH!!! FREEDOM!!! Day, Saturday is Mostly Hungover day, and Sunday is PreDoom day.

Hump day has nothing to do with sex. Unless one wants it to. I like to declare the existence of hump day just to see people's faces. Usually being conservative and all

Wednesday, the middle of the week, implying that you have to get "over the hump" before you can anticipate the weekend. The term was not originally intended to carry a second, more risque meaning.

A term used exclusively by douchebags in reference to Wednesday.

Means Wednesday. Simple.
Also connected to the meaning of Kegnesday in some parts of South Africa.
Does NOT mean the day we get to hump. People are glad it's hump day simply because it's Wednesday ie: downhill to the weekend.....

The middle of the work week, wednesday, or the beginning of the weekend, depending on your level of addiction to alcohol.
The day of the almighty hump day soiree