a subject that can be used to control someone, as a killswitch for undesirable behavior. it is somewhat synonymous with blackmail, extortion, etc.. derived from the act of tying a Lightening bug (the southern term for Firefly) to a thread, so that it can be jerked around in the air, like a dog on a leash.
my friend told me one of his take-it-to-the-grave secrets, so I told him one of mine, as a lightening bug thread.
by non-redneck in the south March 8, 2007