This was posted in alt.callahans a few years back by Dr. Jest (aka Shaun Pike).

Doctor Jest enters the bar in good spirits, and offers the following about The Yukon during the Gold-rush.

Enter two cityborn lads named Carter. Looking for pack animals, they are sold a trio of caribou by a wily local. Hitching up their unusual draught animals to a pack sled they are greeted by a fellow prospective prospector name of Dart who hitches a ride on back of the sled. As they set off, a local wit remarks; It’s the Three-Moose-Carters with Dart hangin’ on.