Having abused Desdemona, an enraged Othello, thinking she is having an affair with Cassio, turns on Lodovico with the following speech, saying:
Yes, you asked me to call her back. See how well she can turn? She can turn and turn, and then turn on you again. And she can cry, sir—oh, how she can cry! And she’s obedient, as you say, obedient. Very obedient—keep crying.—Concerning this—oh, what fake emotion!—I am being ordered home—Get away from me, I’ll send for you later.—Sir, I’ll obey the order and return to Venice. Get away from me, you witch! Cassio shall have my place. And, sir, tonight
I do entreat that we may sup together.
You are welcome, sir, to Cyprus. Goats and monkeys!
In the final line, the animal imagery
echoes all that Iago has been insinuating to Othello and whispering in his ear. Iago, throughout the play, seems as disgusted with sex as he is with human beings in general. He describes it often as an animalistic act, describing lovers as if they are crudely mating beasts.
Iago has painted a false picture in Othello's mind of Cassio dreaming of sex with Desdemona and turning to Iago, sleeping beside him, and kissing him as if he were Desdemona. These images have had the desired effect, and Othello now can't shake from his mind the idea of Cassio and Desdemona having sex like animals. In using the phrase "Goats and monkeys!" he is telling Lodovico that everyone in Cypress mates like animals, but he is, of course, specifically referring to the grunting, lustful sex he imagines between his wife and Cassio.
This imagery reveals Othello's heightened emotional state and the fact that he is not thinking clearly.