The midway point in many sports events. In NFL games, the intermission after the second quarter of the game.
Usually a great time for bathroom breaks, cracking open another beer or making a run to Publix for more wings.
In major events (e.g., the Super Bowl), a time to hold short rock concerts, usually a combination of totally unrelated acts (2001 Super Bowl Halftime Show: Aerosmith, N'Sync, Mary J. Blige, Britney Spears, and some rapper who's name I forget.