As always: in IT, Google is the other half of your brain.
However, if you can't be bothered to self-educate, here are the facts:
The jackelope (Lepus Temperamentalus) is a mammal native to the North American Great Plains. It is often described as a jackrabbit with antelope horns or deer antlers and sometimes a pheasant's tail and/or hind legs. The word "jackelope" is a portmanteau of "jackrabbit" and "antelope."
Their speed, agility, and strong neck muscles combined with comparatively large, sharp antlers make them a match for most predators. Human survivors of jackelope encounters confirm that it is vicious and unrelenting once provoked.
Jackelope milk is a Schedule I narcotic: an opiate roughly twenty-three times stronger by weight than morphine. It is outlawed in many countries, including the United States, leading to a profitable black market.
As female jackelopes sleep belly-up, it is possible to milk them; however the mortality rate of heavily-armed jackelope "milking hunts" is nearly 100%.
The jackelope can convincingly imitate any sound, including the human voice. During days of the Old West, when cowboys gathered by the campfires singing at night, jackelopes could often be heard mimicking their voices.
The jackelope uses this ability to evade hunters via phrases such as "There he goes!" or "That way!"
The most effective way to hunt jackelope is by putting a flask of whiskey out at night. The jackelope will drink its fill and its resultant intoxication will make it (marginally) less dangerous.
Jackelope meat has a taste similar to lobster.The life expectancy of the jackelope is unknown. Tests performed on recovered carcasses show death of old age, with one estimate of its age at death at over 120 years.
An apex predator in almost any environment, jackelopes would soon overpopulate. Fortunately, jackelopes will only breed during electrical storms that include hail. A jackelope litter never exceeds two pups. They consequently maintain a roughly one-to-one birth-to-death ratio.
Given the difficulty of capture combined with their unusual mating habits, it has proved impossible to keep jackelopes in captivity. The Great Plains Zoo and Delbridge Museum of Natural History in Sioux Falls, South Dakota maintains a one-million dollar X-prize for the capture and permanent safe display of a jackelope to the general public. To date, it remains unclaimed.
It's sort of a running gag.
I'm active in some libertarian circles. After seeing my customary avatar, people started using the nickname.