Check the latest meaning and definition of hump below.
“Luncheon” is an extended form of “lunch” (another form of “lump,” as “hunch” is of “hump”).
The hump is an immemorial sign of the French badin-ès-farces.
I'm goin' over thar ter Hump Doane's house—an' reason with them hotheads.
It is just as wonderful whether it is one hump or two humps.
I declare that the hump seemed the one normal thing about it.
He had lost his hump, and they easily persuaded him to come with them.
The hump at first is scarcely noticeable, but develops rapidly.
On the back of the neck there is a hump or swelling, which seems confined to this variety.
If one of them rigs up so she has a hump on her back like a camel, all the others break their necks fixing up humps.
He turned his back and reached over his shoulder to his hump.
hump 1680s (in hump-backed), from Du. homp "lump," from M.L.G. hump "bump," from P.Gmc. *khump-. Replaced, or perhaps influenced by, O.E. crump. A meaning attested from 1901 is "mound in a railway yard over which cars must be pushed," which may be behind the figurative sense of "critical point of an undertaking" (1914). The verb meaning "to do the sex act with" is attested from 1785, but the source of this indicates it is an older word. Humpback whale is from 1725.