For ’tis the sport to have the enginer
Hoist with his own petard.
– William Shakespeare
Hamlet, Act 3, Scene 4. Hamlet says it is good to see the engineer blown up by his own bomb. He knows Rosencrantz and Guildenstern are bearing a letter from evil King Claudius ordering Hamlet’s execution, but he has decided to foil this by replacing the letter with one ordering the letter bearers’ deaths.