UrbanDictionary.com
Squid - A young motorcyclist who overestimates his abilities, boasts of his riding skills when in reality he has none. Squid bikes are usually decorated with chrome and various anodized bits. Rear tyres are too wide for their own good, swingarm extended. Really slow in the corners, and sudden bursts of acceleration when a straight appears. Squids wear no protection, deeming themselves invincible. This fact compounds intself with the fact that they engage in ‘extreem riding’–performing wheelies and stoppies in public areas. Squids wreck alot. Derived from ‘squirly kid’
Though the term is now widely used to describe street riders of questionable cornering skill, questionable judgement in demonstrations of horsepower and braking, questionable judgement in the protective clothing worn, and very questionable judgement in his/her friends, the meaning was actually developed at the racetrack.