So, 'gumping it' is when someone is not quite retarded, but they're like just on that line.
"I need to confess a sin, Father. I worked at a grocery store in my teenage years, I won't get specific. There was this one girl-- are you familiar with the term 'gumping it' --so while it's an ethical conundrum, it's not fucking a retarded person if you were to sleep with 'em. This will come important later in the story..."
Nickname given to bales of marijuana thrown overboard or out of airplanes. Origin is reportedly from members of the US Coast Guard in the area of Southern Florida.
"Base we've got some square groupers floating outside of Miami harbor."