If you don't have something nice to say, don't say it at all ... unless you're a president with an amazing ability to hide an insult in eloquent language.
When Lincoln got mad, he didn't stoop so low as to actually call someone a 'butthead.'
Instead, he said, 'The trouble with [General Joseph] Hooker is that he's got his headquarters where his hindquarters ought to be.' Ouch!
Referring to a lawyer, Lincoln said, 'He can compress the most into the smallest ideas better than any man I have ever met.' Total burn!
Ulysses S. Grant got a little fresh when he said that James A. Garfield 'is not possessed of the backbone of an angleworm.' (No offense to angleworms.)
When talking about Alexander Hamilton, John Adams got pretty heated ... and a little dirty. 'His ambition, his restlessness, and all his grandiose schemes come, I'm convinced, from a superabundance of secretions, which he couldn't find enough whores to absorb.'
On the other hand we have Thomas Jefferson, who didn't try to disguise his insults at all. He called John Adams a 'blind, bald, crippled toothless man who is a hideous hermaphroditic character with neither the force and fitness of a man, nor the gentleness and sensibility of a woman.'
Can't we all just get along?