Where do I find insults by Shakespeare?

There are lots of good places to find insults in Shakespeare.  He has a lot of characters whose main function is to insult others.  And a lot of characters who insult people even if that's not their job.

Characters whose job it is to insult include the clowns or fools in plays (like the fool in King Lear, or the Clown in 12th Night).  Other characters who insult people a lot are Katharine in "Taming of the Shrew" and Kent in "King Lear."

For specific insults, look at any lines of Katharine (or those speaking to her) in the early parts of "Taming of the Shrew."  For insults by a man, look at Act II, Scene 2 of King Lear -- look at how Kent insults Oswald from the beginning of the scene.