Death Pebble 

In skateboarding a small hard to see pebble that when run over will cause your board to grind to an instant halt regardless of how fast you're going, usually sending the skater flying over the front of the board, much to the confusion of onlookers who simply see the skater go flying for no real reason. Usually there pebble leaves a chalkish skid mark showing how far the board slid before the rider was launched which can be used to recover some ego.

If you have never hit a death pebble, don't worry. One will find you and make you look like a poseur.

Death Pebble by Dsky171 July 27, 2016

Death Pebble 

When a pebble (or small rock) get shot through the air by a random object to come into contact with something living causing it to die instantly.

instance 1: bike rider hiting a death pebble and the tire shoots it through the air and it bounces off a tree and plunks someone in the head so they die.

instance 2: when a person on shore doesnt pay attention and see the swimmer in the lake before they try to skip the death pebble across the water, thereby hiting the swimmer in the head causing him to drown and die.

Instance 3. yr first name is Bart and yr last is Simpson and you always cary a sling shot any stone in your hands become a Death Pebble

Death Pebble by CrimsonDream April 17, 2011