The state of being required to be sober but you still drink beer cause no one will notice. Hard alcohol is banned but less potent beer is allowed to increase functionality and decrease the chance of blackout. Usually imposed at fraternity functions where the rules state that sobriety is require but leadership relaxes those rules.
Bro 1: "Sucks we have to be sober tonight for that function."
Bro 2: "No way man, we just have to beer sober! Here drink this beer!"
Bro 1: "Oh yeah! Sweet!"