The Hump occurs when you have to fart (or produce liquid fecal matter). At some point before farting you will feel very ill. If you are able to hold it in for a minute or 2 you will feel right as rain. The time in which you are in pain is known as the hump.
Driver- Dude should I pull over!?
Passenger- No, just a little longer and I will be over the hump.
Being in a bad mood for whatever reason, and projecting the attitude on all others around you. The Hump generally is associated with a Camel and for people possessing and projecting the attitudes of the Camel.
Peter has just been snapping at everyone this morning. It's not like him. What's he got the hump about?