Three surgeons are discussing who make the best patients.

The first surgeon said “Electricians are the best, everything inside is color-coded.”

The second surgeon said “No, I think librarians are the best, everything inside them is in alphabetical order.”

The third surgeon shut them up when he said “No, you’re both wrong. Politicians are the easiest to operate on. There’s no guts, no heart, no spine and no brains. Plus, the head and the ass are interchangeable.”

I like that.

Any really good joke, always has some "kernel of truth" (or is it "Colonel of Truth?") at it's core... yes, I do see a kernel of truth in that many politicians have no figurative heart, spine, brains or guts, yes, that is actually true! That is exactly why the joke is funny.