Ladder

Medieval theologians argued that since a ladder leaning against a wall forms a triangle and a triangle is a symbolic reminder of the Holy Trinity, anyone who carelessly blunders through this mystical space is risking divine wrath! Even when that argument lost itself in history's muddle, condemned Englishmen about to be hanged at Tyburn or some other notable place of execution were required to walk under the ladder that stood against the gallows for convenience of the executioner. In those circumstances, you could say the man was certainly in for a spell of very bad luck.