1. [mid-16C] (UK Und.) a member of a team of confidence tricksters who works as a back-up to those running the fraud; if the victim realizes they are being tricked, the rubber swiftly causes a disturbance, usu. by picking a fight with the earnest bystander, thus allowing their confederates to grab the stakes and run.
2. [early 17C; 1900s–50s] any form of deception or trick.