Every Bill which shall have passed the House of Representatives and the Senate, shall, before it become a Law, be presented to the President of the United States….
But in all such Cases the Votes of both Houses shall be determined by Yeas and Nays, and the Names of the Persons voting for and against the Bill shall be entered on the Journal of each House respectively.
– Article I, Section 7 of the United States Constitution
In case you're unfamiliar, the Slaughter Rule is named after Louise "she wore her dead sister's dentures" Slaughter and it works like this:
The speaker brings a bill containing a list of changes that the House wants to make to the Senate bill to the floor for a vote. When the House members vote for and pass this list of changes to the Senate bill, the House will deem the Senate bill as passed as well, even though the Senate bill itself was never voted on to begin with.
Mark Levin explains further:
In the meantime, we must continue to call, write, plead, and implore. Don’t just call those who are going to vote “yes,” call those who are going to vote “no.” Call the leadership of the opposition and encourage them to throw as many monkey wrenches into this thing as they possibly can.
We’ve been fighting this for a year. We’ve called, we’ve written, we’ve gone to town halls and tea parties. We marched on Washington. But they won’t stop.
Well neither will we.
Say not that thousands are gone, turn out your tens of thousands…It matters not where you live, or what rank of life you hold, the evil or the blessing will reach you all. The far and the near, the home counties and the back, the rich and the poor, will suffer or rejoice alike.
The heart that feels not now is dead; the blood of his children will curse his cowardice, who shrinks back at a time when a little might have saved the whole, and made them happy.