Very Loud Bike Horn
The thunder horn was designed to help the cyclist be heard when you are getting in his way. It gives out a noise at 115 decibels which is louder then the average car horn and just slightly quieter then a Jet Plane. The recommended specs say that you shouldnt use this with in half a meter of someones ear due to it causing damage.
The thunder horn costs $12 from Brando.
Via: GadgetGurus