mad dog

To stare fixedly at someone in a hostile manner. Generally used to convey anger or disdain, can be a signal that a fight is about to happen.

Spell it backwards, see what you get.

To stare someone down in an attempt to demonstrate who's more hardcore (i.e., who has more balls). If both persons refuse to drop their gaze, a fight usually entails.

Slang term for Mogen David wine, especially the fortified-wine MD 20/20 variety. The MD stands for Mogen David. It was shortened to MD for their line of bum wines to differentiate between their more respectable (if no less nasty) line of kosher wines.

Contrary to popular myth, there has never been a wine sold under the name Mad Dog.

cheap liquor, that may cause you to have violent actions or outburst which is what MD (mad) (dog) 20/20 alchol content.

just being a mad bastard

Someone who, during the course of a conversation or debate, becomes increasingly agitated and ends up ranting and raving.

The best way of tipping such a person over the edge is to start chanting "mad dog, mad dog, mad dog", in unison, quietly at first but growing in volume while tapping your nails on the table top. This will guarantee an hilarious end to the conversation.