During the course of the year I do find that there are times when only two beers 12oz-ers can give me a hangover. I think that it may have to do with me needing to drink more water (dried out or under hydrolyzed?) and/or that I am needing some sort of vitamins/minerals in my diet. Such shortfals then adding to the hangover or making it harder to fend off.
However, if a specific liquor consistanly gives you a hangover even with truly minimal imbibbing, that points to allergies or sensitivities that may have no possible offset.