"And You Thought the U.S. Senate Was Incompetent" Dept

From Wikipedia's article on Canada's Goods and Services Tax, a sentence explaining how it came about that the GST was reduced from 7% to 6% despite the opposition of political parties sworn to head off the reduction:

When the legislation enacting the budget was brought forward for final passage, it was accidentally passed by unanimous consent due to parliamentary confusion; neither the Liberal Party nor the New Democratic Party had intended to support the budget.

As talented as Harry Reid and Nancy Pelosi (and their Republican predecessors) might be, I don't think even they can top that one.