Yet another colloquialism for shooting one's load.
I slung my web all over her face.
Sorry I didn't call you last night, I was out slinging web on anyone that would have it.
When in doggy style position, twist your wrist inward to the "thumbs down" position. Place your thumb over her bung-hole and move it back and forth in a circular motion, much like the blades of a helicopter.
Girl to guy: "Give me the Thumbcopter!"
Guy to guy: "I Thumbcoptered her last night - dirty girl"