This is from The Funny Bone [jokemaster@funnybone.com]. Stan Kegel posted it on the groaners listserv.

A butcher just out of trade school, applies for and gets, a job in Northwest America, skinning and cutting up the kills of local hunters. The first job he gets is to cut up a moose to put in the freezer. He finally gets the moose cut up and is putting it into bags and marking them with the contents: chops, rump steak, ribs, sirloin, etc.

When he finishes with the stuff he knows, he is left with a pile of unidentifiable parts. At a loss as to what to do with them, he finally puts them all into one bag and labels them… moosellanious.