Tic
Complex motor tics are typically more purposeful-appearing and of a longer nature. They may involve a cluster of movements and appear coordinated. Examples of complex motor tics are pulling at clothes, touching people, touching objects, echopraxia (repeating or imitating another person's actions) and copropraxia (involuntarily performing obscene or forbidden gestures).
List of motorcycles by type of engine
The Tandem Twin is where the cylinders are longitudinal, and have two cranks geared together. A tandem twin is effectively a pair of geared singles, and is to be distinguished from an inline twin. Tandem twins are suitable primarily for two-stroke racers.