Sentence:  He would wear a phony diamond ring to flash in your eye, and he would have an “<WSD>eyeballer</WSD>” or kibitzer in the audience who would make a sudden noise or otherwise distract you while you were shooting. 
Meaning of the word marked with <WSD> tags:  A secret accomplice who surreptitiously watches the competition and interferes by causing a distraction to prevent the opponent from getting a good shot.