n. the amount of beer you would have to give up drinking by choosing entertainment at a non-drinking establishment.
Tickets for the student section at the university basketball game are general seating. Grant and Phil chose not to go early enough to get good seats, because the oppbeertunity cost was too high at 4 beers. Instead, they sat in the back of student section, foregoing the opportunity cost of better seats at the game.
You could say Grant and Phil prefer 4 beers (each) and bad seats to good seats.