A wonderful mix of a Danger Wank and a Stranger.
One sits on ones hand until it is numb, masturbates with the feeling that someone else is performing the task and shortly before orgasm shouting: "MUM!" with a hint of urgency in ones voice. This will stimulate the mother and the aim is to finish choking one's chicken and clean up before the mother arrives at the location of masturbation. Varying difficulties can be achieved by altering the distance between the mother and oneself. For extreme stranger danger, place oneself in the room next door with the door wide open.
a young lad performing a strangerdanger...
Young lad - "MUM!"
Mum - "coming!"
Younge lad - "not before me!"