The act of getting 0 headshots in a multiplayer match with BR starts. The name was coined after AlkalineProdigy; a Bungie, Halo 3, and all things Xbox, uber-fanboy, went 9-10 during Team BRs on Foundry in Social Team DLC. The fact that he was given a BR, 5 minutes, and a small map, obviously means nothing, because even his oh-so-coveted recon armor could not help him to get even 1 headshot.
Link to game: http://www.bungie.net/Stats/GameStatsHalo3.aspx?gameid=932969512&player=AlkalineProdigy
It's sad to think anyone could get 0 headshots with BR starts. AlkalineProdigy is the only one who could do this, that is why it is called the Alkaline Perfect.