An action which was quite widespread in New York and possibly in other locations during the early 1990's. When someone would say something incorrect or stupid, any party who witnessed this could proclaim "Gill!", and then proceed to rub the back of the offender's neck with their hand, causing minor irritation to a red mark, depending on the severity of the given gill. One could also proclaim "Save mine", which would allow the person to administer the gill to the offender at a later point in time. It should be noted, however, that if the person committing the slip-up takes notice of their folly before anyone calls a gill on them, they can say "pause" and then could not be subjected to a gill. If someone calls gill after the initial speaker says pause, it's a gill on them. Giving gills is great but getting them isn't.
Person 1: "Yo, Iverson dropped 50 on the Sonics last nite...pause...he dropped 43."
Person 2: "Gill"
Person 1: "Chill, I already said pause. Save mine."
Person 2: "Damn."