In the midwest in the late nineties we would say, "Get a keg," or "Roll in a keg."
A party that happened to have a keg was just a party with a keg. A party with the purpose of drinking beer from a keg was a kegger, whether it was a fraternity party or a party at someone's house. Usually fraternity parties had more resources to buy kegs, so they had keggers more often.
The typical keg is 15.5 gallons. Sometimes people would say, "Get a barrel," or "Roll in a barrel," but a keg is techincally half a barrel. The smaller kegs we would call half kegs, which were technically quarter barrels.
We would call the little gallon or gallon and a half containers with self contained taps pony kegs, although I think a pony keg is technically a half keg.