Petard.

...as in "hoist upon one's own petard". ('Blown up by your own bomb', for you of a more modern linguistic bent.)

That just about sums up result of the the Liberals successful call of no-confidence in the Harper administration of Canada. Seems the Tories are hauling out the big guns in some ridings already, and the numbers for the Libs don't look so good:

The poll has now placed Mr. Harper at levels of support above 40 per cent for three straight days. That level is traditionally seen as the yardstick for forming a majority government.

As readers here might recall, the Conservatives missed an outright majority by 11 seats the last time things went to the polls.

It is looking much more promising this time. Heh.