When someone farts and it sounds a little or a lot wet, the issuer of the fart should say "gumrunners" to make sure that the others in the area know that his or her underwear is safe and sound and that it wasn't a "shart".
I was just working around the yard at the Jandon, out of nowhere comes the wettest juiciest fart from my back end. I vigorously say "GUMRUNNERS" to let everyone within range know that I didn't crap my pants.
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.