Mad dogging (or doing a mad dog) is a slang term for looking at someone in an aggressive, crazy, or provoking way.
There are a lot of situations where the expression is applicable, but commonly it is used when somebody is visibly expressing that they seek conflict.
An essential feature of mad dogging is establishing eye-contact with whoever we wish to mad dog. In other words, this is just another name for a staredown.
The expression is an idiom, and it comes from the common occurrence of two dogs staring each other in the eye viciously before going toe-to-toe.
This behavior can be observed in most mammals too, humans are no exception.
Coming from American street slang, mad dogging was a relatively unknown expression for many until the late 2000s.
In 2008, a murder was reported in the media as a result of a “mad-dogging” staredown in New Mexico.
In the following years, several other similar crimes were referred to as “mad dogging” in the media, which eventually popularized the term.