A 1980s sociological term that later became a term of derision.

Refers to activities of social interaction engaged in by groups of men, either because it was fixed in the Y-chromosome or because women preferred to avoid such activities.

Proper male bonding could include:

drinking bouts
hunting or fishing trips
brawling (see: The Quiet Man)
watching sports on TV

or any combination of the above. For example, in the comic strip Bloom County, male bonding consisted primarily of sitting around in your underwear, drinking beer and watching football on TV.