Set a bucket of cold water on a concrete or other fire resistant surface.
Rinse out the bottle thoroughly. Wrap the thread around the bottle at the point where you want the bottle to break. (The thinnest area of the bottle is best. If the glass is too thick, this trick may not work.) Wrap the thread around the bottle thirty to forty times.
Put on your rubber gloves, in case you get lighter fluid on your hands.
Squirt the lighter fluid on the thread, soaking it. Squeeze the thread a bit so it soaks up as much lighter fluid as possible. Wash the gloves with soap and water.
Hold the bottom of the bottle with one hand, and light the thread with the other. Turn the bottle on its side a bit and rotate it. If any fluid on your gloves catches fire, dip your hands in cold water immediately.
Let the thread burn until it goes out, then immediately drop the bottle into the cold water. If it doesn't break on its own, quickly grab the bottle and apply pressure to the heated area to break the bottle.