A specific type of motorcycle, typically distinguished by it's aerodynamic 'hunched-over' seating position and high power to weight ratio. Often favoured by stunters, who choose the bikes because they are light and easy to perform tricks (such as wheelies and stoppies) on.
Crotch rockets are not always Japanese motorcycles, Italian companies such as Ducati manufacture quite high-quality crotch rockets as well.
Also known as 'sportbikes'.
The Ducati 999, Suzuki GSXR1000 and Yamaha YZF-R1 are good examples of ~1000cc crotch-rockets.
"Hey can I have a ride?" Goose it to make 'em hold on tighter, brake hard for mush-action.
"Driver's license, registration, proof of insurance please." Heard more often than above unless you don't stop...
Motorcycles are broken down into general categories. Off road, Track, Cruisers ( incl. Harley Davidsons, Kawasaki Vulcan, Yamaha Roadstar), Sport Touring (Honda ST1300), Touring (Honda Goldwing) and Sport.(Honda CBR600, Yamaha FZ6) Sport bikes are very fast highly mobile bikes where the rider is low and leaning forward. The bike is generally a cafe race style. A Crotch Rocket is the slang term for Motorcycles of the Sport category. The term is derived from their incredible speed. The previous definition of "Non-Harley's" is patently false. I have a Honda Goldwing and it is definitely not a Crotch rocket.