HARDBODIES-This word may seem obvious. But I have seen the confusion with it. Basically every biker I know or have dealt with uses hardbody to describe a good looking women.
 

CROTCH ROCKET-commonly refers to a motorcycle that was built for speed. Whether bought or built by the owner. Rice burning bullet bikes are a good off the top of my head choice for description purpose only bike. 
 

BULLET BIKE- racing bikes. And even though Harley has some that are primarily for racing. And buell deserves some mention for production bikes using a sporster v-twin. cafe racers is also a word used to describe these bikes
 

CHOPPER-Generally can mean several things. If a brother takes his ride and leaves it mostly stock Just trims it down with accessories such as drag bars closed in lighting system and the list goes on. It can be called a chopper. But generally chopper means extending the length of the bike. And making it a totally customized bike built just for you. This generally means cutting and changing the dimensions of the frame. changing the ride height and adding parts built to fit that bike.
 

BRAIN BUCKET or LIDS- what else but a helmet. .
 

RUB-Rich Urban Biker
 

LONG FELLOW-refers to the Harleys first few year models. Long fellows came equipped with a single cylinder motor till 1909. They then came with the option of a v-twin which was not a very popular motor. It relied on suction to open the intake valve. Which proved very unreliable. In 1911 they equipped the v-twin with the more reliable mechanical pushrods for the intake and exhaust valves.
 

FLATHEADS-refers to Harleys manufactured from 1930-1948. in which they moved the valves to opposite sides of the combustion chamber for more power which was needed in the heavier motorcycles. Which where reminiscent to what we see today.
 

KNUCKLEHEAD-Introduced in 1936. The valves in the knucklehead were moved to the top of the combustion chambers. And made in 61 cubic inchs. In 1937 Harley incorporated the first dry sump oil system. Harley also offered a 74 cubic inch engine in 1941. The knuckle received it's  nick name by the appearance of the heads which look similar to the top of a hand.
 

PANHEAD-Introduced in 1948. Received its nick name due to its valve covers look of an upside down cake pan. The panhead didn't change much from the knuckle in internals. But it came equipped with aluminum heads. Again for more power for the growing weight of the motor cycles. It also depressed the heat better. in 1955 Harley modified the pans by installing a quieter more efficient lower end. Pans were also the first v-twin to come with an electric starting system in 1965.
 

SHOVELHEAD-Introduced in 1966. with new heads which worked better with the upgraded lower end. The shovel also came with hemispheric combustion chambers. Which they had already introduced in the sportsters in 1957. The shovel came in a 74 incher than an 80 incher. It recevied it name for the look of a coal shovel.
 

EVO-This is what we know as today's Harley motors. Introduced in 1984 the evo was the most radical change Harley motors saw. With aluminum cylinders as well as new aluminum heads designed to decrease oil leakage. Side-squish combustion chambers and flat pistons. A new lower end designed for electronic ignition for better spark control. All these changes came about as a result of higher big-brother emission standards. which the shovel just did not seem to be able to handle. The evo has proven to be the most reliable and maintenance free v-twin
 

SQUID- Squirrelly Young Kid 

One Percenter -  See the Information here