The hour long period of time starting at midnight (in the morning) on one's twenty first birthday (in the US). This hour is spent continuously drinking, usually beer. Essentially it involves making sure your lips never leave a glass as a friend should have the next round ready after the current one is done.
Man, you drank 20 beers last night during your hour of power!
A Jaguar automobile, typically a XJ.
Wow, that jag is such a jew bentley.