A) One's head starts involuntarily thrashing violently back and forth at an alarming rate.
B) One's speech is reduced to an unintelligible series of grunts and guttural utterances.
Once the above has been achieved, conversation should immediately be shifted to the subject of torturous, gory methods of murder. Hangovers should ideally involve waking up feeling AND looking like one's face has been smashed in with a hammer.
Residents of New England, particularly those hailing from Buffalo, New York, will often find this feat much simpler than peoples residing elsewhere.
Bar patron #2: Yeah, I feel sorry for his head, neck and throat tomorrow morning.