During sex, the woman is on top, and once the man announces he is going to cum, the woman dismounts and procedes to spank the man's cock against his stomach as the cum shoots up toward his face to create a firecracker effect.
Man: "Oh Baby! You make me so hot! I'm gonna' cum!"
(woman springs into action)
Woman: "Firecracker Spank!!!"
(woman vigorously slaps man's cock against his stomach and watches him shield his eyes from the cum sparks)