For a person of experience to make an error in a situation where she should know better.
Often used by soccer fans in the UK when describing a naive or careless error by a professional player.
"Blimey... that's a bad mistake by Beckham. A real schoolboy error!"
Definition of Schoolboy error...
"getting the basics wrong" ... especially when you should know the answer
Expecting to be able to buy tickets "on-the-door" when U2 are coming to play in the Village Hall that night... to discover that all 250 were sold out months ago...
Schoolboy Error: (n.), (der. old English), A mistake, often trivial, clumsy, dimwitted or easily avoided. Generally shameful in hindsight, but without cause for embarassment, owing more to circumstances or instantaneous bad luck, rather than serious incompetence of behalf of the maker. Derived from the "trial and error" psychology present in Victorian-era English public schools.
Upon dropping the soap in the Violent Offenders' Wing of Barwon Prison, Eric cursed his schoolboy error.
Dr. Feynmann lowered his glasses as the fruit of twenty minutes labour yielded an unwanted result: E = mc^2/0. "Well fuck me", he said, turning to the class. "I seem to have made a schoolboy error."
Making the most basic of simple mistakes, worthy of ridicule, particularly when you should know better
School boy error!!
I just made a school boy error!
He school boyed!
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.
And here comes Keane for the winner....Oooooooh and he's missed, and left the black right over the pocket for Swann to tap in...
school boy error is when you make a simple yet stupid mistake. you feel stupid after you've done it.
"i just locked my keys in the house!"
"haha, school boy error!!"
Offering one's hand to other person to shake, only to retract and to laugh in their face, whilst repeating said words. Pioneered by Soccer AM.
"Aha! Schoolboy Error! Sit Down! Shut up! And tidy your room!"