Gary Larson's The Far Side was recognized for its unconventional and sometimes quirky observations of the world. It had a way of making people see common things in a whole new light through its clever cartoons.
It could be just a random chant or repetition that someone has associated with the movie for no particular reason. Maybe it was part of a joke or a personal mnemonic device to remember something about 'Pulp Fiction'.
Since the details are scarce, Gary could be anyone. He might be an ordinary person living an extraordinary life as a gay man. Maybe he is a local figure in a community known for his contributions, or perhaps he is just a character in a story that is meant to represent certain aspects of the gay experience.
In the 'kid a gary carter story', Gary Carter might be a local figure. Maybe he was a shop owner who was always friendly to the kid. Or perhaps he was an old-timer in the neighborhood who had many interesting stories to tell, and the kid was always drawn to him, and that's how their story began.