schoolboy error

The most basic of errors. An error so simple, and avoidable, that anyone with an ounce of credibility or experience in that field should not be commiting it. A mistake that should only be made by school boys still in training for that particular task. Especially used when referring to playing games of pool in pubs, or occasionally during snooker. Schoolboy error can be heard ringing out by jeering onlookers if for instance a participant missed a sitter = he should have potted it as it as so simple, that thereforehe is reduced to the level of a lowly school boy playing his dad for the first time.