Article I, Section VII, subsection 2 of the Constitution deals with the procedure for bills to become law. The President must either sign the bill or return it (veto) to the congress within ten days of passage. Congress has the power to override the veto with a two-thirds majority of each house. However (and this is the tricky part):
"If any Bill shall not be returned by the President within ten Days (Sundays excepted) after it shall have been presented to him, the Same shall be a Law, in like Manner as if he had signed it, unless the Congress by their Adjournment prevent its Return, in which Case it shall not be a Law."
In political parlance, it's called a "pocket veto."
So, I guess the President could just go up to Camp David, kick back and watch TV while the press, pundits and poobahs spin themselves into ever decreasing circles, eh ???