In Act IV, scene i of As You Like It, Rosalind (disguised as a man going under the name of Ganymede, but pretending to be Rosalind—long story) and Orlando share the following exchange:
This demonstrates one example (of a hundred thousand) of the "horns of the cuckold" joke. The English Renaissance Stage could not get enough jokes about cuckolds. The idea is that a cuckold (a husband whose wife has been unfaithful to him) had invisible horns. Hilarious.Rosalind: Nay, and you be so tardy, come no more in my sight: I had as lief be wooed of a snail.
Orlando: Of a snail?
Rosalind: Ay, of a snail; for though he comes slowly, he carries his house on his head; a better jointure, I think, than you make a woman: besides he brings his destiny with him.
Orlando: What's that?
Rosalind: Why, horns, which such as you are fain to be beholding to your wives for: but he comes armed in his fortune and prevents the slander of his wife.
Orlando: Virtue is no horn-maker; and my Rosalind is virtuous. (IV.i.49-61)
The following image shows George Lucas giving "bunny ears" to Steven Spielberg:
What's the connection? Well (without intending to cast any aspersions on either the former or the current Mrs. Spielberg), the gesture indicates that he has the horns of a cuckold.
I don't suppose that most people realize they're issuing a pretty severe insult whenever they make "bunny ears" in a photo. And, on April First, I don't suppose you really believe that there's a connection between the two.
Perhaps two paintings (one of which seems to be a reimagining of the former) will serve to convince you. Here, a particular character in the Commedia Dell'Arte is given the horns of the cuckold in a manner very similar to the way Lucas is giving them to Spielberg:
A Scene from the Commedia Dell'Arte, c. 1580
François Bunel, Actors of the Commedia Dell'Arte (c. 1590s)—Detail
The gesture has remained, though its meaning has largely been lost to the mists of obscurity. But remember it the next time you're tempted to give someone "bunny ears" in a photograph—it has a long and dignified history. Well, it has a long history, at least.