A hell-horn is a fifth sized bottle of low budget alcohol, usually whiskey, which is not palatable enough to use in a mixed drink, but is tasty enough to drink (yak) straight out of the bottle after many hours of drinking low budget beer, i.e. Busch, Rainier, and Keystone (don't be fooled by the trendy lite and ice versions) which comes in 3 different sized cans (called classic, tallboy and tally, respectively) and is emblazoned with an animal, usually a deer, elk, or moose on it's label.
The owner of the hell-horn is a tiny blonde man who is wiry and spry, listens to AC/DC, and is usually the oldest person at a party, but fits right in, and who has invented many pipes and bongs out of everyday household items. These items are the envy of head shops worldwide. There is usually a dead animal in his yard every time you visit him.
I went to an after party and my friend, Craig, approached me with a bottle of Potter's whiskey. I told him to give me a yak off that hell-horn and I don't remember anything after that.