cuckold's horns
Cuckold's horns is a hand gesture traditionally placed behind the head of an unwitting man (the cuckold) to insult him and represent that his wife is unfaithful. It is made with the index and middle fingers spread by a person standing behind the one being insulted. The "symbolism has been forgotten but the insult remains" as in modern culture, this same gesture is known as bunny ears.
This tag has been aliased to bunny_ears_(gesture) (learn more).