Running a bluff is an age-old technique for enhancing one's reputation for business acumen, but the gambit can backfire in spectacularly embarrassing fashion if your bluff is called.

  White bullet An unwary hostess tries to pass off a cake purchased at a bake sale as her own handiwork.

  White bullet An impressive-sounding phone conversation is revealed to be phony.

  White bullet A boss fires an indolent office boy and pays him off on the spot, only to discover that the dismissed employee worked for someone else.

  Green bullet Law firm secretary sends caustic reply to senior associate's e-mail request for a £4 cleaning bill reimbursement.