Definition of double sap:
(v) :
To click twice on a touchscreen.
(n) :
(idiomatic) A tactical shooting technique of pulling the trigger of a weapon twice in quick succession to deliver two shots to the same target zone.
(n) :
Two shots or bullets fired in such a way.
(v) :
To shoot twice in rapid succession.
(n) :
(by extension) A bombing strategy where the same target is attacked twice, with the second attack targeting rescuers and mourners.