Usually used in reference to a person who is extremely angry and of below average height and weight. A Garganese will also tend to be a drunk and a chain smoker and a lover of fast food. If you meet one, you should be prepared for an angry conversation that you will probably walk away from feeling very, very offended.
Johnny: Did you see that drunken little fucker in the bar talkin all that shit to me about Obama.
Jasper: Yeah, he was such a Garganese.