The act of making a "raspberry" sound with one's mouth, while it is between a pair of labia. The vaginal equivalent of the "motorboat".
"Her baloney flaps were so large, I couldn't help planting my face in there and doin' the twatcopter." or "It's a lot harder to pull off a resonant twatcopter if she's got a 70's porno bush."
1. A worthless human being with little or no value to society. A perpetual fuckup. A person whose only legitimate purpose in life would be to serve as a literal human coaster for some female to rest her twat on.
Guy #1: Hey what did you do last night?
Guy #2: I was just fucking Liz.
Guy #1: Was she nice and tight?
Guy #2: Not when I was done with her. I slammed that pussy so hard, it blinked like a twatclops!