"Whenever I learn something new, I forget something else" - Hommer Simpson.
Doif is the brand of beer Hommer drinks, a parody of Duff in the original The Simpsons.
When Hommer has the Doif in episode 3 he enters some sort of trance. When he later tries to drink Foster's beer he immediately vomits, possibly implying that Doif produces addiction and aversion to other beer.