So get a gallon of milk, and IF they have eggs, get a dozen (gallons of milk). Basically this is an if statement meaning if X is true, do this. Well normally we think get a dozen would be get 12 eggs, but because "have eggs = true" that meant get 12 gallons of milk. The opposite would've been eggs=false and he'd come home with 1 gallon.

I'm not a Dev so I can't write the code better, but I understand the language enough