Meaning of "Pork belongs in sandwiches, not DC"

Trump addressed a Libertarian rally, to many boos and jeers.

Many of the people were holding signs with the slogan “Pork belongs in sandwiches, not DC”

What does this even mean?

Congress over spending by adding pet projects to bills which benifits the congressional district they represent is called pork. Its a common practice in Washington DC.

^^^ Yes.

Here is a short explanation with an example.

Thanks for the answer, both of you.

It was essentially outlawed in 2011 but has been brought back:

It amounts to about 1/1000 of federal spending, and almost all of the projects are good.

Beside, a little pork grease works wonders against partisan legislative gridlock.

Eliminating “pork barrel politics” (which is loaded phrase in and of itself) was one of those things that sounded like a good intentioned no-brainer but turned out to have some unintended consequences.

One of those consequences is partisan gridlock, a situation where no Republican will ever vote for anything Democrats support, and vice versa. While tossing in a measly million dollar project for a congressional district into a bill in exchange for a vote may feel like buying votes, it’s kind of how politics works, and most of those projects are good and necessary.